Widest tire on S197 without major mods?

[Foosh442]

Anybody running AIX/ST2 in an S197? Wondering what size tire I can fit under my car ('05 Mustang GT) without doing any major modifications (stock body/fenders) Currently in AI trim with 275/35-18 on 9.5" wide rims(44mm offset) but exploring other options. Any input would be great, thanks.

[UBR]

Ryan Winchester ran most of the season in ST2. He had 315s on his car. Not sure of the offset or mods. His fenders didn't look any different than ours. Not sure if he is on the forums much, but I drop him a post on fb.

 

j

[Red Tornado]

We run 305/654/18s in world challenge on 18x10 rims with no issues at all. My guess it up to 315's on 11 inch rims can work in back and front likely close.

[UBR]

Here's the reply back from Ryan.

 

"We have 18/11" wheels and the biggest that won't rub would be 305 the 315 rubbed so we stopped using them. Not sure what the offset is I'll have to check."

 

He's running 25 hrs of Thunderhill this weekend and flew out to Ca this morning. NOt sure when he'll have a chance to check.

 

j

[UBR]

Ryan just clarified. No mods on the car. 315s fit fine on the rear but rubbed on the front.

 

j

[bluebandit48]

wider is not always better.. I seem to remember the weekend at mid ohio when Ryan switched from ST2 to AI, went from the 315 to the 275 and went faster.

 

Dean will tell you the same thing... wider is not always better.

 

we had I think it was 315s on a sn95, and we ended up running a 295 because it was a little better.

[RWinchester199]

I currently run 315 in rear and 285 up front. This is the fastest combo that I have used to date. The weekend at midohio when i switched to 275 the car was slower lap time wise. Bigger isnt always better but in my case the 315 285 combo is the fastest on my car. My wheels are custom made from CCW and are built for the rear of the car, I use a spacer up front which is the reason for the smaller front tire. If the offset was set up for the front the 315 would fit just fine. In the interest of being able to use the wheels on all four corners we chose not to have a set for the front specifically. Hope this helps. My wheels are 18/11" I have zero fender modification. If we rolled the fronts we could run the 315, it barely rubs with the normal fender.

[Foosh442]

Great info, thanks guys

[Fair]

Realistically an 18x10" wheel with a 285-305mm tire fits really well, but there are very few 18x10's you can buy off the shelf that fit this chassis and don't weigh a lot. I've done a good bit of wheel testing on the S197 Mustang, and with the right offsets (custom 3-piece wheels), you could possibly fit up to an 11" wheel up front and up to a 11.5" to 12" on the rear. The rear is limited somewhat from the factory swaybar. These sizes would take fairly different offsets front to rear, with the rear being a LOT more positive than the front.

 

 

I bought all manner of 18x9.5", 18x10" and 18x10.5" off the shelf 1-piece wheels - to try to find something lightweight that would fit this chassis, front and rear, without poking out of the fenders or rubbing the 14" Brembo calipers. And without going to a 3-piece wheel (which tends to get both pricy and heavy). Most of the 9.5" to 10" wheels for sale are OEM reproduction offerings that are heavy, cheap, and garbage - and most of it fits poorly, too. I found nothing under $700/wheel or under 25#/wheel that fits the S197. I got so tired of looking that I built my own 18x10" wheel instead:

 

 

I have the first production batch of these 18x10" ET43 D-Force wheels (19.2 lbs, $309) arriving next month. These bolt to the S197 Mustang, front and rear with no spacers. Light, strong, affordable.

 

 

I've been testing these on our 2011 GT the street, autocross, and road courses for months. They clear the 14" Brembo front brake calipers with an inch to spare.

 

I was kind of hoping AI was going to jump to a 10" wheel this year, then I'd have a great big batch of racers wanting them, but no luck. Oh well, they will still work great on HPDE, street, or AIX cars. I'm thinking of making 17x9.5" and 18x9.5" wheels to fit AI and CMC cars next (both made to just meet the minimum weight rules and be affordable), if this batch of 18x10" wheels sells well. Already working with both 3th gen F-Body and Mustang folks to figure out the ideal offsets to build.

 

Good luck

[pederb]

Cortex Racing has the solution for 315

 

http://www.cortexracing.com/store/suspension/2005-2012-mustang/

 

Cheers