have addressed this several times green
i used 275/40's (michelin pilots) on my 97 GT rear wheels and used 275/40'(Dunlop Sp Sport 5000's) on my 99 GT
yes, it looked MUCH better from the rear and greatly improved dry performance but in really heavy rains and or light to heavy snows,...you loose traction due to the "plowing" nature of a wider tire. it does look really good in the rear. do not recommend them for the front however, it "pushes" the wheels and tires out too far for my taste
Putting 275's on the stock rim will improve straight line acceleration and the appearance, but it will hurt handling in the corners. The reason for this is that for the sidewall to do its job it needs to be perpendicular to the road surface. If you put a wider tire on a narrow rim the shoulder of the tire is wider than the rim. This forces the sidewall to be angled like this \^^^^/. ( the hats are the tread)This in turn causes a lot more sidewall flex and hurts the cornering. In corners sidewall flex is bad!
Straight line performance should be improved because you have a larger contact patch.
Appearance is improved because you wheel wells get filled out better!
It just depends on what your goal is. If you want to drag the wider tires are better. If you want to autocross or do laps around a track stay with the 245's
If you really want to put 275's on you should go with a rim that is at least 9" wide and even better 9.5" or 10".
i accept your explanation but the stock rims aren't exactly narrow and my SOTP/Gut feeling was MUCH better cornering performance in BOTH my 97 and 99 GT's as well as straight line!!!! the sidewall might have been "pushed out' a little compared to the 245/45's but if so, it was very little. i used new 245/45's in the front of BOTH vehicles and all i can say i felt my improvments in both straight line AND cornering performance.
maybe i'm wrong but the way my butt slides around usually doesn't lie!
(you'll have to trust me on that one!-LOL)
The information I'm sharing comes from somone I know who works at Griggs racing. (without a doubt they make the absolute best suspension for Mustangs) I put 275/40/17's on Cobra R rims on my 96 GT because it was lowered and it need the wheels and tires to fill out the wheel wells. The Cobra R's were 9" wide and his recommendation was to go with 255's instead of 275's for the same reason I explained in the prior post. He had 255's on his 93 Cobra with the Cobra R wheels and Griggs suspension. It was the BEST handling car I have ever been in. The car absolutley defied the laws of physics. I share the knowledge because it came from a very reliable source.
I most likely (at this point anyway!) Will not take my car onto a a road race track. I KNOW it will end up at the strip though (on slicks, 15 inch). I was mostly wondering how it looked on an 8 inch wide wheel, and if it fit at all. I would have to guess that on the twisties on the streets it would handle as well or better than 245's would. But, would they look OK on the front?
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