Yet another wheel and tire thread. Sorry...

[That11GtGuy]

Okay, so I know there are about a million threads on wheel and tire fitment, and trust me, I've seen most of them. However, none that I have found have given a straight answer on what I would like to know.

Here's my dilemma. 2011 Mustang GT with 3.73 gears, and I have 2 options picked out:

18x10 APEX EC-7 with 285/40r18 OR 285/35r18

19x10 SVE r357 with 285/35r19

So my question is, for the 18 inch wheel, which is better? A 40 aspect ratio or a 35? I'm not entirely sure if a higher sidewall is better for handling or if a lower one is? Also, if someone could explain to me how the gearing impacts tire and wheel selection? I've seen that mentioned a few times but I really don't understand why that would play a role.

And then the dreaded opinion that is everywhere...18 vs 19x10? I would like it to be 10 wide as the car sees a majority street use, and 11s would be pulling me out of my lane like crazy. And I know that for race tires, most are in 18 diameter, but I just don't know how 18s would be on the street.

I apologize for the long winded post, but this is something I have tried researching on my own but come up even more confused.

 

[JDee]

Lower aspect ratio is better for handling, though worse for ride. Gives a stiffer sidewall. 11" rims are the way to go, if you get rut wander with a 305/30 on an 11" rim there is something else wrong, likely alignment or steering gear issues. I run 305/11" with -3.5 negative camber and I have never had any worse problems with the car wandering around on the road than with the stock tire/wheel.

These are heavy cars and they need all the tire/rim you can get under them. 11's are kind of standard, there are folks doing 12's and 13's now. Going with 10's will be a dead end if you are seeking maximum performance. 18s are best if you are intending on running used slicks, and 18's in general may be cheaper vs 19". But there are getting to be more 305 track tires available in 19" sizes now and the price has come down a lot lately.

The tire diameter will affect your overall gear ratio simply because of its height. Shorter tire will lower your effective gear ratio, taller tire does the opposite. Going from a 35 aspect tire to a 30 aspect tire puts me slightly over my desired redline on the longest straight where I most often run. There's calulators on the web to figure this out, here's one: https://www.willtheyfit.com

 

[That11GtGuy]

Lower aspect ratio is better for handling, though worse for ride. Gives a stiffer sidewall. 11" rims are the way to go, if you get rut wander with a 305/30 on an 11" rim there is something else wrong, likely alignment or steering gear issues. I run 305/11" with -3.5 negative camber and I have never had any worse problems with the car wandering around on the road than with the stock tire/wheel.

These are heavy cars and they need all the tire/rim you can get under them. 11's are kind of standard, there are folks doing 12's and 13's now. Going with 10's will be a dead end if you are seeking maximum performance. 18s are best if you are intending on running used slicks, and 18's in general may be cheaper vs 19". But there are getting to be more 305 track tires available in 19" sizes now and the price has come down a lot lately.

The tire diameter will affect your overall gear ratio simply because of its height. Shorter tire will lower your effective gear ratio, taller tire does the opposite. Going from a 35 aspect tire to a 30 aspect tire puts me slightly over my desired redline on the longest straight where I most often run. There's calulators on the web to figure this out, here's one: https://www.willtheyfit.com

Okay, cool! I'll be sure to check that site out. Thank you!

 

[Bill Pemberton]

I agree with JDee to a point , but I would suggest going with a 315 and I do not think you will have much of an issue with wandering , but since your main focus is Autocrossing , once you slap on the 18x11s you need all the rubber you can get. DaveW and Dave_W hopefully will pop in with info for you because you will be in the CAM-C class with the rims and the majority of the drivers at the SCCA Solo Nationals are on 315s.

I would suggest the BFG Rival S 1.5 for your Autocross set up , and they work pretty darn well for occasional track events.

 

[EF1]

I understand your desire to stay away from 11" wide wheels. They require a fair amount of negative camber, spacers, and/or coil overs to clear on these cars, which are not always the most street friendly. The guys that are chasing contingencies in TT and W2W will always say go to an 11" or wider wheel with a 305 or larger tire. I can't argue with their logic. These are heavy cars and more tire on the ground does help, but not everyone is looking for that last couple of seconds.

I have a dual use car that I play with at the track. I am not running competitive classes, just HPDE groups for fun. If I was building a dedicated track car I would certainly look at 11" wide wheels (class permitting) and everything that goes along with making them fit, but I don't think it is that import for someone getting started. Remember that NASA Spec Iron cars are restricted to a 9.5" wide wheel with a 275 wide tire.

I think it is more important to get out on track. Plan modifications/upgrades as you gain experience to correct handling characteristics that you do not like or that are holding you back.

 

[That11GtGuy]

I understand your desire to stay away from 11" wide wheels. They require a fair amount of negative camber, spacers, and/or coil overs to clear on these cars, which are not always the most street friendly. The guys that are chasing contingencies in TT and W2W will always say go to an 11" or wider wheel with a 305 or larger tire. I can't argue with their logic. These are heavy cars and more tire on the ground does help, but not everyone is looking for that last couple of seconds.

I have a dual use car that I play with at the track. I am not running competitive classes, just HPDE groups for fun. If I was building a dedicated track car I would certainly look at 11" wide wheels (class permitting) and everything that goes along with making them fit, but I don't think it is that import for someone getting started. Remember that NASA Spec Iron cars are restricted to a 9.5" wide wheel with a 275 wide tire.

I think it is more important to get out on track. Plan modifications/upgrades as you gain experience to correct handling characteristics that you do not like or that are holding you back.

Alright, thanks for the input! And on a side note,

I understand your desire to stay away from 11" wide wheels. They require a fair amount of negative camber, spacers, and/or coil overs to clear on these cars, which are not always the most street friendly. The guys that are chasing contingencies in TT and W2W will always say go to an 11" or wider wheel with a 305 or larger tire. I can't argue with their logic. These are heavy cars and more tire on the ground does help, but not everyone is looking for that last couple of seconds.

I have a dual use car that I play with at the track. I am not running competitive classes, just HPDE groups for fun. If I was building a dedicated track car I would certainly look at 11" wide wheels (class permitting) and everything that goes along with making them fit, but I don't think it is that import for someone getting started. Remember that NASA Spec Iron cars are restricted to a 9.5" wide wheel with a 275 wide tire.

I think it is more important to get out on track. Plan modifications/upgrades as you gain experience to correct handling characteristics that you do not like or that are holding you back.

Okay, thank you for your input! On another note, how are Steeda Sports on East TN roads? Those are something I'm looking at and, well, you know Tennessee roads haha.

 

[EF1]

Alright, thanks for the input! And on a side note,

Okay, thank you for your input! On another note, how are Steeda Sports on East TN roads? Those are something I'm looking at and, well, you know Tennessee roads haha.

The Steeda sports ride fine on the roads here. I actually made my first round of suspension mods to correct some handling characteristics that I didn't like before ever thinking about tracking the car. I didn't like the brake dive and rear end squat while decelerating and accelerating, respectively. I also didn't like the wheel hop I was getting on hard launches.

The first round was the Steeda Sports, Koni STRT shocks/struts, and what is typically marketed as rear lower control arms, but more appropriately called rear trailing arms (as to not solicit a response from the terminology police). The car is much more composed than stock. It is a little stiffer, but not harsh. I think it drives better on the road than stock

 

[Bill Pemberton]

The key is that11GTGuy has autocrossing listed as his main focus, and frankly if he reads the rules and makes virtually no changes to his car other than some better shocks, it appears he could go F Street. This would not cost him much money and he could buy a smaller rim, but even then most everyone runs a wider tire than a 275.

No one likes running a 275 tire in Spec Mustang, American Iron , etc. but those cars also can weigh quite a bit less - one of the rules drivers hate because they go through tires pretty quick. The Tire Guru ( Blacksheep 1 ) will preach to everyone , this car is undertired, so would suggest 11GTGuy goes to SCCA.org and checks out the rules for Solo Competition. If he wants to make changes like camber plates, tune, suspension pieces eventually, he might as well get the bigger rims , etc. because he will be running in CAM-C. Going to HPDEs , Time Trials ,etc. would not be a problem, but the last thing I would imagine he would want would be to make changes and then ending up at an autocross on a set of 275s and getting destroyed by rubber on the ground even if he has talent, imho.

Just my polite suggestion, since so many of my friends with Mustangs run at the Solo Nationals site , and the bulk have moved up to CAM-C because they want to make changes F Street will not allow. F Street would be a great place to run for awhile , and if he wants to spend little money except maybe sticky rubber and a set of squared rims ( check rules for correct sizing as you there is a variance allowed though limited ) . Tires are the number one mod after seat time to get faster, and it is often one folks view after spending thousands on other things , when they will give the quickest and most substantial improvement of any expenditure.

 

[That11GtGuy]

The key is that11GTGuy has autocrossing listed as his main focus, and frankly if he reads the rules and makes virtually no changes to his car other than some better shocks, it appears he could go F Street. This would not cost him much money and he could buy a smaller rim, but even then most everyone runs a wider tire than a 275.

No one likes running a 275 tire in Spec Mustang, American Iron , etc. but those cars also can weigh quite a bit less - one of the rules drivers hate because they go through tires pretty quick. The Tire Guru ( Blacksheep 1 ) will preach to everyone , this car is undertired, so would suggest 11GTGuy goes to SCCA.org and checks out the rules for Solo Competition. If he wants to make changes like camber plates, tune, suspension pieces eventually, he might as well get the bigger rims , etc. because he will be running in CAM-C. Going to HPDEs , Time Trials ,etc. would not be a problem, but the last thing I would imagine he would want would be to make changes and then ending up at an autocross on a set of 275s and getting destroyed by rubber on the ground even if he has talent, imho.

Just my polite suggestion, since so many of my friends with Mustangs run at the Solo Nationals site , and the bulk have moved up to CAM-C because they want to make changes F Street will not allow. F Street would be a great place to run for awhile , and if he wants to spend little money except maybe sticky rubber and a set of squared rims ( check rules for correct sizing as you there is a variance allowed though limited ) . Tires are the number one mod after seat time to get faster, and it is often one folks view after spending thousands on other things , when they will give the quickest and most substantial improvement of any expenditure.

Sorry for the confusion here. I put autoX as my only experience. I would like to do autocross to improve my motor skills, but the end goal for me is HPDE, and then eventually I'd like to get a NASA license and do some W2W and Time Trial. So I'm open to, and would prefer, a wider wheel than 9.5. Sorry again for the confusion Bill, I can change that to avoid anyone else being confused. Regardless, thank you for your input.

 

[Bill Pemberton]

No need to change your experience level and thanks for the clarification, as that will help all of us giving you our ideas and thoughts. We may all have differing views , but the nice thing with all the folks offering their kind advice , whatever meets your personal feelings will likely hit a hot button for you.

My simple, first advice , especially as a NASA Instructor , would be to advise a student who wants to do HPDEs with the end result being to do Time Trials, is view the rules for the class they want to run in and if the rim size or tire is not restricted , get the biggest meat you can, because the fast drivers will be on wide rims. Go to nasaproracing.com , enter rules and then plug in info under the TT3 Class. You likely do not know your exact weight or rear wheel hp, but you can guess and that will give you some ideas on what you might be able to do ,along with reading the rules for that TT3 Class. Since you are wanting to do HPDEs first , this will just give you an outline of things you can do to benefit your car the most.

Best of luck , and enjoy your weekend.

 

[Grant 302]

Regardless of your intended path, I suggest running 11” wide wheels. You’ll eventually need or want them. Might as well buy them now. You can put any of the sizes mentioned so far on them. I currently have 275 on my 18x11 Apex.

I also suggest worrying less about your setup and upgrades and focus most of your budget on seat time and consumables (and safety if you haven’t already) for now.

 

[Dave_W]

Gearing based on tire size - every revolution of the tire moves the car forward a certain distance. Just as changing the ring & pinion gear ratio changes how far forward the car moves for each revolution of the driveshaft, changing the rear tire circumference does the same thing. If you've got a 3.31 R&P, going to a short enough tire would make it feel like you've got a 3.55.

The 2021 SCCA Solo rules are out, and Street Touring Unlimited (STU) is now allowing RWD N/A cars to run 315mm wide 200 treadwear tires on 11" wide wheels. And STU allows swapping to larger rotors & non-stock calipers, so a 14" Brembo brake swap is legal (as is a 15" S550 swap), which would also be a big help on track if you've got the smaller brakes. STU also allows changing/adding springs, shocks, sway bars, suspension bushings (e.g., rubber to urethane but not to full metal bushing or rod ends), camber plates, rear lower trailing arms, rear trailing arm relocation brackets, upper trailing arm (but not the chassis-side mount), panhard bar (use an adjustable one to re-center axle after lowering) or Watt's link. So pretty much everything you would change on a daily driver with some HPDE days, and then some. STU does not allow using a non-stock front lower control arm or ball joint if you're using camber plates, and does not allow "bumpsteer kits" for the tie rod ends. Front seats can be changed in STU but they must be fully upholstered and "The seat, including mounting hardware, must weigh at least 25 pounds and must be attached using the OE body mounting holes/studs. Additional mounting points may be added." Staying in STU instead of CAM-C means you're not running against K-member swaps with full wishbone front suspension and twin turbos. I know autocross isn't really your focus, but it's always nicer if you do show up to not be completely outgunned in your class. As someone on an SCCA committee once said, "The rules for CAM make Street Mod look frugal." Both STU & CAM have a 200 treadwear minimum; using a DOT-legal "R comp" like a Hoosier A7 or R7 puts you in E Street Prepared; using a full-race slick like takeoff Continental Grand Am tires puts you in C Prepared.

So, I think to decide between 18" or 19" wheels, you should look at whether you want to upgrade to the S197 14" Brembo package, the S550 15" Brembo package, or something else. Once you've picked your front brake package, check what wheel sizes (in your price range) fit over the brakes. Then take a look at what tires are available for those size wheels. As I mentioned in your other thread, running a lower-grip tire will teach you to feel the grip limit at a lower and safer speed, and generally give you a wider window when "breaking away." Also, a narrower tire is better supported on a given wheel width than a wider tire; the narrow tire will feel "crisper" on turn-in. Just don't overdo it (i.e.,no #StanceLife). Use Tire Rack's specs for each tire model to see what wheel width is recommended for a certain tire. Generally, 19" tires are more expensive than the same tire in 18".

 

[Norm Peterson]

Okay, cool! I'll be sure to check that site out. Thank you!

Be careful.

I've yet to see an online tire or speeds-in-gear calculator that takes into account the effects of tire distortion down where it contacts the pavement.

What's happening is that as the tread passes through contact with the pavement, it "compresses" slightly in the circumferential direction, meaning that the tire's effective rolling radius is not the same as what you'd calculate from the tire's nominal dimensions or sizing - even if they were a dead-on match.

A good estimate of this effect is 3%, though for any given tire make/model it can vary a little either way from there. 3% is meaningless in street driving, but it's enough make a difference when you're looking to avoid having to choose between upshifting at some particular mph and chugging along on the rev limiter. I'm looking at avoiding 3rd at autocross, or having to upshift to a way-too-tall gear on a road course where 3% can sometimes make a difference.

I suppose you could use the online calculators and correct its speeds (downward) by 3%, or you could ignore the calculators entirely and do your own math using the tire mfr's listed revs/mile and the transmission and axle gearing.

Maybe just for grins sometime, pick a tire size and calculate from its measured diameter how many revolutions it would take to travel a mile and compare that against the listed revs/mile. I bet they'll be close to 3% different.

3.142 * (TireOD / 12) = feet per revolution
5280 / [feet per revolution] = calculated revs/mile


Norm

 

[Norm Peterson]

And then the dreaded opinion that is everywhere...18 vs 19x10? I would like it to be 10 wide as the car sees a majority street use, and 11s would be pulling me out of my lane like crazy.

Not necessarily. I don't notice it when I'm on the street with the 18x11's (and 285/35 MPSS). Tramlining is more related to the tires (I'm not 100% sure, but I think that gets into ply steer and conicity), with some tires being noticeably worse than others. Alignment might be more critical, though.

Personally, I think 265/xx tires on 10" wide wheels would make for a solid street combination.

And I know that for race tires, most are in 18 diameter, but I just don't know how 18s would be on the street.

Other than the matter of available sizes in the kind of tire you're looking for, I'm not seeing any problem with 18s just because they're 18s unless you get to the point where the 14" SVT/Brembo front brakes aren't enough.


Norm

 

[KazarS197]

This is a great thread even though it is a "another wheel and tire thread"! After months of research and trying to figure out what is in my opinion the best bang for the buck along with the the thoughts that being domestic with high numbers for multiple years and Ford Racing products were available I purchased a 2012 GT in October. Trying not to derail too far. What I did not know even after research is the complexity, amount of variations and additional vehicle changes that are required as the width goes up to optimal, fitable track size. I truly enjoy all of the input from experienced and seasoned TMO members!

@That11GtGuy here's how I had to break it down as a complete newbie and still have no idea which setup I may go with.

I looked at the S197 Wheel and Tire Fitments Guide numerous times and still referencing back and forth as I decide. For me I see the @APEXRaceParts wheels at the best price point. I did the math for maxed out price- for example 19 x 11 SM-10 with 305 Cup 2's $3700 ish + tax , mounting and shipping. If Apex does a group buy this spring figure at least $250 off and no mounting or shipping if you do as a wheel/tire set.

During my process of research I ran into and had to ask myself while just planning on HPDE's for now:

If I end up decent then maybe I'll try timed stuff or an actual racing structure. For now my focus will be keeping one the track and off other vehicles....

1. Do I want to stay with a 275 or 285 size and not have to do and additional spending - just wheels, tires, upgraded brake pads and fluid and learn the car and have fun? Well the car I purchased was moded and much more HP than stock, had a basic suspension upgrade and stock brakes. That's not going to work for me I'll have to feather the gas all of the time if I get on it.

2. Do I "need" / "want" to gradually push my car to it's full capabilities with wider tires? Yaaaa lets go for it! Here's when I really had to research more and truly ask myself if I can afford that choice. This hobby will be "expensive" at least for me.
- The guys have extensive knowledge - heavy car 3600lbs ish - Put as much meat under as you can fit. If you do not need the width now you will in the future as you advance. OK ya I'll decide to pony up the cash go with the max size before I have to do modification to my front fenders - 305's. With most brands but there are some that might just be a tad taller.
- "What the hell? " I ask myself. Oh I can only run those tires if I have camber plates and 3 degrees of camber to clear everything.
* Ok I'll have to order camber plates.
* Wait the plates that I'm ordering will need the strut towers cut so I can maximize the camber plates so I can get to 2.5 degrees negative camber.
* I need then installed, towers cut and an alignment.
* Can I do myself ? Nope! I'm mechanically inclined but with my luck will rent a spring compressor and hurt myself. Watching a how to vid prob will not work for this one.
* Can I find a race knowledgeable shop that can do everything at one shot to save labor - camber plates, towers and alignment? Done - scheduled.
- I'm planning on a square setup so also need front spacers. OK I'll just get the spacers too. Nope- not going to work. I find out that I need longer wheel studs. Do I purchase Ford Racing hubs or do I order studs and press the old ones out and and new ones in. Can I do the work? Do I have a friend that has a press? Do I have to pay?
- Will my stock brakes be able to handle the 305's. Nope. I already did some but now need to do more research on how to frugally put together a Brembo package. 4 piston will work. Can I afford the 6 pots? Again how much work can I do myself?
- Other stuff I will / might need - some sooner than later. Harnesses, tow hooks. SNELL SA 2010 helmet or better ( only certified through 2022)- I found new/used once one for 50 bucks.

One reason I ask myself all of those questions is I hate spending money for something and redoing work on something that I already did. I fugure in the long run it's actually cheaper to go with the "best" up front. It may take me longer to save money and time to actually hit the track but I will be satified and not have ask myself the question " what if I would have" . I'm not going to be mostly street and occasional track. There's guys here that are full race that have way more mods and improvements that what I may be doing. I just wanted to give you and idea of a cost and butterfly affect of what I found with thinking about going with wider wheels and tires. I have to be honest my plan is sending me about 3 grand over what I thought that it would cost me. I'm pretty sure that I am not the only one that has found this out. Some might be in the 10's of thousands... I tried to keep everything in my post as pertained to me so you could kind of look at it as an outside person rather than saying this is what you need. I learn much by seeing someone else do something or hearing their experience or process. Maybe this post will help you maybe not. The truth is we can only do what we want within our financial limitations. Some more some less. I will tell you only one thing. You have to do what is best for you.

Mark

Edit: I missed with the 305's I will be forced to do the rear bump stop bracket relocation. I'm sure I missed many other things...

 

[stevbd]

OP, if I understand your goals correctly, and if you are really looking for a mostly street setup that you can comfortably take to the track, I would absolutely get the square apex 18x10 with a good 300tw tire in a 275/40/18 or 285/40/18. Something like the MPSS or similar.

Advantages: Easy button setup, great daily driving, no tramlining, no hydroplaning, no huge camber required to fit, no other mods required such as camber plates, racing hubs, longer studs, spacers, etc.; fits over virtually every brake setup out there; easy to rotate, very proportional and balanced setup with an otherwise mostly stock '11 GT. The tires won't let you down but neither will you be going so fast that you have to start immediately upgrading other systems to keep the car balanced.

Disadvantages: You won't ultimately be as fast as a 305 or 315 200tw or race tire.

I have run a 275/40/18 MPSS for years with lots of HPDE days in my '11 GT and it's been excellent.

I recently stepped up to 305/30//19 RE71 and for sure they are a blast on the track but it requires a lot of other mods to work right and I don't really see it as a true "street" setup. You absolutely can drive it to the track but every day going to work? Not really. But if you are just looking for the best track setup, then yes, I absolutely agree you shouldn't waste time or money with small tires but instead you should just go straight to as big as possible.

Finally, if you do decide to go with a true street-track dual use type setup, I would go with a taller 40 series tire. 285/35/18 with 3.73 would be pretty buzzy on the highway I think. If you don't care about that, as said the 35 will provide a little better handling.

Good luck and have fun.

 

[Apex Wheels]

For me I see the @APEXRaceParts wheels at the best price point

Yup

You are not forced to do the bumpstop relocation with 11"/305 rear setup, it's just an option for someone if they are really bothered by the inner lip of the wheel potentially resting on that bracket while the axle is unloaded. It's never a scenario you'll experience on track, or if you do, you have bigger problems. I would say most users, including myself, don't modify that bracket.

We sell a lot of 11" setups to customers who already own 10" or narrower setups if that says anything. I always recommend people to run 11s if they have any desire to get faster and push the car/driver to what it's capable of. That said, there is nothing wrong with 10" wide setups and there are plenty of fast cars running 275s and 285s. All else being equal, a modern Mustang will be faster on 11"/305s than it would on 10"/275s.

 

[John48]

I am very happy with the 305/30/19 11" wheel setup on my 2014 V6 Mustang for autocross Cam-C class. Of course
camber plates and wheel spacers are needed. Don't think I would want to run that size on the street though, quite
pleased with my summer-only 245/55/17 tires on the factory 7" rims for daily driving. Not to hi-jack here, but what
would be the advantage - if any - to switching to the STU class for 2021? I did the typical suspension & CAI/header/
tune mods but no internal engine changes. I also changed the rear gear from 2.73 to 3.73 but don't see mention in
the STU rules for gear changes.

 

[Bill Pemberton]

I would probably stay with CAM-C over STU, since there are some nasty little nimble beasts , with lots of boost running in that Class , Nationally. Plenty of Subaru STis and EVO 9s, throw in their standard AWD and it is a quick Class often faster than CAM-C.

 

[John48]

Thanks Bill. Looking at the car elligibility for STU, which even includes some sports cars & those AWD's, I see your point.