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Yet another wheel and tire thread. Sorry...

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Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
I also changed the rear gear from 2.73 to 3.73 but don't see mention in the STU rules for gear changes.
SCCA has a basic "catch-all" philosophy for such situations . . . if the rules for your class do not specifically permit doing something (and the class is not built on a lower-prep class that does permit doing it) it's not allowed.


Norm
 

Grant 302

basic and well known psychic
New to TMO here, 285 on 11's ? Is this safe for track use

Yes, absolutely.

Wanted to stay in SCCA TT T3 class, 285 biggest tire for that class.

11” wheels will let you use the whole tread. Many people don’t know what it’s like to use a wheel/tire combo that is that ‘stretched’. And with the lack of that experience, will disagree with the benefits.
 
Do
Yes, absolutely.



11” wheels will let you use the whole tread. Many people don’t know what it’s like to use a wheel/tire combo that is that ‘stretched’. And with the lack of that experience, will disagree with the benefits.
Does running a stretched tire change the way you manage tire pressures. I fell like I should run higher pressures to keep the bead seated, thus loosing the advantage of using the whole tire tread. Plan is to run 18x11s with 285 rt660s in SCCA TT at VIR in March. This is the first time with the 11s, i have been running 10s with 275s (340 TW).
 

Grant 302

basic and well known psychic
Does running a stretched tire change the way you manage tire pressures
Yes, but not for any concern over the bead remaining seated.

Compared to the same tire on a narrower wheel, I find it easier to run slightly lower pressures to manage the balance between grip and wear.

And since you’re running 275 on 10” wide (which I have also done) it should be somewhat familiar.
 

Bill Pemberton

0ld Ford Automotive Racing Terror
8,425
8,356
Exp. Type
Time Attack
Exp. Level
20+ Years
Blair, Nebraska
Blue GTS, what tires do you happen to be using? If you later decide to run with NASA in their Time Trial groupings you will likely be able to use those 11s to their full extent. Unlike some of the racing Classes , which some groups are pretty similar, the TT rules for SCCA and NASA are quite a bit different. The wide rims do give you a better chance to take advantage of the differences if you find more activity with one group over the other in your area. I am have been a member of SCCA for 40 years and I will admit I am a little confused by the tire rulings, as it puts many cars that run in certain Classes in Solo Competition in having to switch tire mods to be quite competitive -- just my observation. Good luck and you are getting plenty of good advice to help you realize there should not be any real concern about your rims.
 

Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
New to TMO here, 285 on 11's ? Is this safe for track use
No problems at all. Once mounted, tire beads tend to gradually relax toward the positions dictated by the wheel bead seating surfaces anyway. They're somewhat 'pinched' before mounting, which shouldn't be taken as an indication of where the beads will always try hard to get back to.

11" is the max-recommended wheel width for 285/35, which implies that it's an acceptable fitment for unrestricted use from the tire industry's own point of view. In actuality, max and min recommended are not hard limits (per a tire guy from an engineering-profession forum), so being half an inch outside max-recommended for 285/30 for track use should still be OK. Might look a little weird, but so do some of the combinations that autocrossers have used over the years.


Norm
 
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Norm Peterson

Corner Barstool Sitter
939
712
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
Plan is to run 18x11s with 285 rt660s in SCCA TT at VIR in March. This is the first time with the 11s, i have been running 10s with 275s (340 TW).
Expect sharp turn-in response. From Tire Rack's test,
The steering on the Falken was precise, alert, and highly responsive to the point that sometimes our drivers had to make a small correction because they received more than expected.
Stretch-mounting tires also tends to sharpen their response.

So I'm thinking that "slow hands" will be a good thing here.


Norm
 
Currently running 275 FS Indy 500s on 10s. Got the 11s to run 315s in camc. Been running HPDE and autox for 5/6 years, generally 3/4 HPDEs and 6/9 autoxs yearly. Did a TT as last event last year and really enjoyed it and wasn't very far off the pace. So figure sticky tire will but me there. End goal is 11s w/315 autox, 10s w/285 TT, and OEM wheel/tire when car sets in driveway. Don't think i am ready for NASA, believe NASA is a little more competitive then I'm ready for. Thanks to all for the input.
 
225
177
Exp. Type
Autocross
Exp. Level
Under 3 Years
Colorado Springs
Y'all keep talking, I need to know this stuff. Im currently on 17s with huge sidewalls and all seasons. Went to PPIR time trial practice day last weekend and man it was a bit easy to lose traction. Was a lot of fun, but not the fastest on a set of all season 235s. Been looking at moving up to 18 x 10s NOW and then considering all the changes next year or so needed for 18x11s later.

So it sounds like on a set of 18x10s, can I get away with going up to a 285 with no issues, rubbing, etc?

Now I need to solve for best dual purpose tires (more reading existing threads). Maybe look at brake upgrades next year.
 
been going through everything on line also for fitment, I want a track set of wheels and tires and plan on keeping the PP1 wheels for daily driving. I've decided to go with SVE 10"/11" in combo, Im not willing to do what needs to be done to get 11" wheels under the front, I don't plan on doing anything more than HPDE. I think being honest with what you are doing is key, if your going to race go for whatever floats your boat, I go to the track to get better and drive the car in a manner that would put me in jail on the street and for some reason I keep missing the trophy ceremony for HPDE :). think Ill go with the GY Supercar F1 for tires.
 

Bill Pemberton

0ld Ford Automotive Racing Terror
8,425
8,356
Exp. Type
Time Attack
Exp. Level
20+ Years
Blair, Nebraska
I would still suggest getting a set of 18x11s Apex, they are hub centric , and the rotation of tires is so important for longer tire life doing HPDEs. Sure you might have to get a front spacer and get longer ARP studs , but frankly those bigger meats up front will also give you better turn in and overall cornering in my humble opinion. I think you will find that 75% of us had staggered rims at one time , got rid of them and bought squared and are just trying to give our advice to others, not out of being all knowing, but out of Trackrat Compassion that you don't spend all the money we spent finally finding out square set-ups work the best. We are a compassionate, enthusiastic and empathetic bunch here , so aren't you glad you found this site, ha?!
 
1,289
1,113
Exp. Type
HPDE
Exp. Level
5-10 Years
Philly Metro Area
So it sounds like on a set of 18x10s, can I get away with going up to a 285 with no issues, rubbing, etc?
Probably. I have Conti ECS 285/40-18 on 18x10 45mm offset wheels for the street. I use 3mm spacers on the front because I wasn't comfortable with the 1mm clearance without them. If you get ET43 or especially ET40 offset wheels you should have no problem.

For the track I run 18x10 ET43 Apex EC-7 wheels with 295/40-18 Falken RT615K+ tires with the same 3mm spacer. The current EC-7 wheels by Apex are now ET40. If I had them I wouldn't need the spacer.

The section widths for each brand/model tire are different so it depends on that too.
 
1,289
1,113
Exp. Type
HPDE
Exp. Level
5-10 Years
Philly Metro Area
Now I need to solve for best dual purpose tires (more reading existing threads). Maybe look at brake upgrades next year.
If you're moving to wider tires I would do the brake upgrades sooner rather than later. ESPECIALLY if you decide to go 18x11. And don't forget brake cooling ducts.

Oh, and the 18x11s may need caster/camber plates to keep them tucked in under the fenders.
 

Bill Pemberton

0ld Ford Automotive Racing Terror
8,425
8,356
Exp. Type
Time Attack
Exp. Level
20+ Years
Blair, Nebraska
Coz is quite right but Camber plates are one of the other early mods you should consider, as they help keeping your front tires alive, as well as helping with turn in and cornering. Without the negative camber you will eat the outside edge of your tires as you become quicker. Regardless of the size of your rims and tires the plates help you get the negative camber so beneficial to the front heavy Mustang.
 

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