Tires and Wheels for Autocross and Road Racing

[AGilmer590]

Hey, I have a 97 Mustang GT 4.6L. I am looking to get new tires and wheels for autocross and possible future road racing. I am looking for 200TW tires the same on all 4 corners. Currently it has the factory 17x8 wheels. I am looking at some 18x9 wheels and am not sure about the offset. I am struggling to determine the offset when figuring which wheels to match with the tires. Also, I am debating about the width of the tires as well. I am trying to get away with minimal modifications to make everything fit. One issue I have been running into is that the car has the Cobra drums and calipers on the front and the rear end has been swapped with the 2000 Mustang GT rear end. I don't know if that makes any difference when it comes to clearance issues on the rear. I am looking for some advice and thoughts about getting this job done and it actually work well for autocross and road racing.

 

[xr7]

No advice here, but, that's a good looking car!

 

[AGilmer590]

Hey, I have a 97 Mustang GT 4.6L. I am looking to get new tires and wheels for autocross and possible future road racing. I am looking for 200TW tires the same on all 4 corners. Currently it has the factory 17x8 wheels. I am looking at some 18x9 wheels and am not sure about the offset. I am struggling to determine the offset when figuring which wheels to match with the tires. Also, I am debating about the width of the tires as well. I am trying to get away with minimal modifications to make everything fit. One issue I have been running into is that the car has the Cobra drums and calipers on the front and the rear end has been swapped with the 2000 Mustang GT rear end. I don't know if that makes any difference when it comes to clearance issues on the rear. I am looking for some advice and thoughts about getting this job done and it actually work well for autocross and road racing. Manuel transmission

View attachment 66524

No advice here, but, that's a good looking car!

Thank you

 

[Bill Pemberton]

Do what so many have done here and contact APEX --- there is a TMO Representative ( Cory ) you can contact just clicking on their Sponsor Link.

Concerning Tires the best place to check is at TireRack ( another link here ) and contact Luke Pavlik ( ext. 4362 ) for a large variety of choices for your autocross/track needs. Many of us on here can give you specific tires to use, but depending on what you want to run the most ( autocross or road racing ) , there are better choices for each that may be a little compromise for your other track/course endeavors.

Many will run a 200 Treadwear Rated tire , as it is required for the CAM classes in SCCA Solo Racing, but many also work quite well for HPDEs track time. Good idea to go with a bigger wheel and hopefully some guys who have bumped up a lot on their SN95s can chime in on spacers, wheel fitment , etc. Between TMO members, APEX and yourself I am sure you can get your Mustang set up solid for CAM T.

 

[AGilmer590]

Do what so many have done here and contact APEX --- there is a TMO Representative ( Cory ) you can contact just clicking on their Sponsor Link.

Concerning Tires the best place to check is at TireRack ( another link here ) and contact Luke Pavlik ( ext. 4362 ) for a large variety of choices for your autocross/track needs. Many of us on here can give you specific tires to use, but depending on what you want to run the most ( autocross or road racing ) , there are better choices for each that may be a little compromise for your other track/course endeavors.

Many will run a 200 Treadwear Rated tire , as it is required for the CAM classes in SCCA Solo Racing, but many also work quite well for HPDEs track time. Good idea to go with a bigger rim and hopefully some guys who have bumped up a lot on their SN95s can chime in on spacers, rim fitment , etc. Between TMO members, APEX and yourself I am sure you can get your Mustang set up solid for CAM T.

Thanks for all the info and thoughts. I will be sure to check into all of it.

 

[blacksheep-1]

The rear on the 99s and up (as I recall) is a bit wider, but not sure how much.
If your rules allow, I would run 18 inch wheels, there's a lot of options in 18 tires especially used race take offs.
Apex and Tire Tack are good resources, if you want to go the lo buck (but not necessarily the best) route there's CJ's pony parts, and Late Model Restorations. Generally 10 inch rear and 9.5 fronts are pretty common.

 

[AGilmer590]

Sounds like good info to check out. I know a guy with a 95 who has 18x10 wheels with 23 offset. It looks like it is working good for him.
Thanks for the info

 

[Speedboosted]

We (APEX) recently came out with our SN-95 specific EC-7. 18x9.5" ET22 that fits a 275 all around without issue. Big brake clearance and a gorgeous deep concave face are added bonuses

https://www.apexraceparts.com/shop-...tang/18x9-5-et22-apex-ec-7-mustang-wheel.html

 

[Bill Pemberton]

Always nice to be on a Forum where the Sponsors actually chime in ! Apex is one of the most active and they seem to constantly be in the process of making new rims and offsets for Mustangs of all Generations.

 

[TMSBOSS]

Apex is one of the most active and they seem to constantly be in the process of making new rims and offsets for Mustangs of all Generations.

Five sets for my two Mustangs so far.

 

[Bill Pemberton]

Running CAM you want to get as much meat down as you can so if you get an 18x9.5 look at some of the tires that are 285 ( Falken RT660 for instance ) or when chatting with Luke , ask him if there is a 295 that would work on a 9.5 inch wheel ( some tires run narrower than others). Obviously check with your friend who has the 18x9.5s already.
Good luck and maybe someone will chime in who is running a wider wheel on a SN95?

 

[RinerAuto]

Increasing your wheel to 18 will help a lot. More tire availability and brake clearance. I'd recommend a minimum of 18x9.5. Wider can be fitted but may need some trimming or spacers to fit on the front. Rear you should have plenty of room, especially with the New Edge rear in there. I think its 1" wider than the SN95.

As far as offset, that's just one part of the equation. What you really need to look at is backspacing, which not advertised but can be calculated from wheel width and offset. In case you're not familiar offset is distance between mounting surface and wheel centerline. Backspacing is distance between mounting surface and inside wheel lip. So backspacing is what will cause interference if too high.

The equation for backspacing (approximate, but really close) is: (Wheel width+1)/2 + (Offset/25.4)

So take a stock 03/04 Cobra wheel which is 18x9 ET25 gives a backspacing of 6". A Y2K Cobra R is 18x9.5 ET20 but also has 6". 6" seems to be the sweet spot for front end fitment and minimum rubbing. You will probably need steering locks (standard on cobras) to limit steering and keep tires from rubbing on swaybar.

With all that said when I was looking for wider wheels for this season, I made a spreadsheet with all the dimensions of wheels I liked to find what I could fit. I ended up with the Kansei KNP 18x10.5 ET12 (6.22" backspacing) and added a 1/4" spacer to get back down to that 6" backspacing number. I have a Youtube video going over my fitment and things I have changed to make them fit. The 200TW tires that are all the rage right now are the Falken RT660s, which I also run and love.

 

[AGilmer590]

Increasing your wheel to 18 will help a lot. More tire availability and brake clearance. I'd recommend a minimum of 18x9.5. Wider can be fitted but may need some trimming or spacers to fit on the front. Rear you should have plenty of room, especially with the New Edge rear in there. I think its 1" wider than the SN95.

As far as offset, that's just one part of the equation. What you really need to look at is backspacing, which not advertised but can be calculated from wheel width and offset. In case you're not familiar offset is distance between mounting surface and wheel centerline. Backspacing is distance between mounting surface and inside wheel lip. So backspacing is what will cause interference if too high.

The equation for backspacing (approximate, but really close) is: (Wheel width+1)/2 + (Offset/25.4)

So take a stock 03/04 Cobra wheel which is 18x9 ET25 gives a backspacing of 6". A Y2K Cobra R is 18x9.5 ET20 but also has 6". 6" seems to be the sweet spot for front end fitment and minimum rubbing. You will probably need steering locks (standard on cobras) to limit steering and keep tires from rubbing on swaybar.

With all that said when I was looking for wider wheels for this season, I made a spreadsheet with all the dimensions of wheels I liked to find what I could fit. I ended up with the Kansei KNP 18x10.5 ET12 (6.22" backspacing) and added a 1/4" spacer to get back down to that 6" backspacing number. I have a Youtube video going over my fitment and things I have changed to make them fit. The 200TW tires that are all the rage right now are the Falken RT660s, which I also run and love.

Hey thanks for the good information. As I have been studying about tires and wheels, my plan was to go to the 18” wheels an a wider 200tw tire. However, I had some difficulties when ordering wheels that would be the size I wanted in the price range I wanted. Due to pandemic is what they all said was the reason for not having anything in stock.

Since then, another driver who drives a factory 5 roadster offered to sell me his old set of wheels and tires for $550. It as mostly what I was looking for except they are 17” wheels.

They are
315/35/zR17 with 17x10.5 and 27 offset bullitt wheels, NITTO NT555 on the rear. 275/40/zR17 with 17x9 and 24 offset bullitt wheels, NITTO NT05 on the front.



They will do for the rest of this season and probably next season. Unless I find a good deal on some 18” Wheels in the future. Since I got these tires I have gained around 5 seconds on my autocross time.

Besides, it will give me a chance to test a theory I have about smaller wheels.

BTW, I have watched you videos. They are good!

Thanks again!

 

[PatientZero]

The easy option is 18x9.5 around +20 offset with 275/35-18. This is usually the size marketed toward SN95's and the size of the 2000 Cobra R wheels. The problem is the rear wheels are sunk like a battleship so grab a set of 1" bolt on spacers. This is with a 1" spacer on the back.

 

[RinerAuto]

Hey thanks for the good information. As I have been studying about tires and wheels, my plan was to go to the 18” wheels an a wider 200tw tire. However, I had some difficulties when ordering wheels that would be the size I wanted in the price range I wanted. Due to pandemic is what they all said was the reason for not having anything in stock.

Since then, another driver who drives a factory 5 roadster offered to sell me his old set of wheels and tires for $550. It as mostly what I was looking for except they are 17” wheels.

They are
315/35/zR17 with 17x10.5 and 27 offset bullitt wheels, NITTO NT555 on the rear. 275/40/zR17 with 17x9 and 24 offset bullitt wheels, NITTO NT05 on the front.

No problem, information is meant to be shared. Yea the pandemic caused a lot of supply chain issues. Also trying to buy tires in spring is always tough as that is when everyone is trying to buy race tires. So buy early if you can. Good deals are always the best. My first autocross street tires were also the NT05s. That setup will serve you well for now and should be easy to sell later on. Or find someone selling the same setup and use the 10.5 for autocross and 9 for street.

Buying new wheels and tires is expensive and that money can be better spent somewhere else when can find used parts. I have three sets of wheels for my car, two used sets and then the Kansei's that I just bought new. Then good 200tw tires are almost just as expensive as Hoosiers. We all know it's an expensive hobby though.

BTW, I have watched you videos. They are good!

Thanks man. I appreciate that.

 

[Bill Pemberton]

Depending on what groups you are running with tire choices will land you in various classes. I run road courses primarily with NASA, but there is not a single group ( imho ) as up to date or active in Cone Killing as the SCCA. Tires are the huge game changer, and I would definitely talk to a lot or super active Autocrossers on here or in your area. You will often find a tire you think is quick in your group is actually mid pack or slow in SCCA, or worse, you will find yourself bumped to a different Class. This advice is simply based on the reality if you get serious with Autocross you will definitely run with SCCA and eventually get to the Premier Pylon Party in Lincoln,Ne. each September. It is still the largest automotive participation event in the World , where 1100-1300 Pylon Pilots congregate for the National Championship. I have autocrossed on and off for 40+ years and I hesitate to count how many times I ended up with the wrong tire at the Championship - sometimes just the wrong size with the same brand.

The one thing I would look into this year is getting 4 matched tires, it seldom ever works to have different tires on a car ( for autocross or on a road course ) because the compounds, tread patterns,. etc. are different even with the same brand.