I'm looking at a good deal on BFG R1-S slicks in 245 40 18. To mount on 18x9.5 +45. They are 25.5" tall. I currently have 25" tall tires and they are right at the fender liners. Can I just raise my ride height .25" for .5" taller tires? Any downside to that? Front it already very low on recommended stock Ohlins settings.

 

If it's nearly rubbing, i would raise it equal to the increased height of the wheel (1/2")

I find this a good wheel calculator

Custom wheels, rim tire packages

 

People used to use the 275/40/17 tires on the rear which are ~25.6" tall. Rear shouldn't be a problem. Not sure about fronts though... Maybe search on that tire size to see if people had any fitment problems on the front?

 

The issue I personally run into with taller than 25" tires is rubbing behind the headlight bucket. The prev owner of my car ran 255/40/17s and shredded the inner liners (and the wiring harness at some point). With my 265/35's that are about 25.3", i'm catching whats left of the inner liners and getting close to full lock it rubs metal forward of the tires, this is just in parking lots so very annoying. May be ok for track use since you're not likely to use full lock.

 

I've raised my car to accommodate taller tires as I couldn't find the tires I wanted to use in shorter sizes. I ended up having to raise it almost a full inch. Outside of losing looks it raises the center of gravity and at times it seems like it wants to roll over or lean more during cornering. Could also be that I went to a stickier tire too so hard to tell for sure. Ultimately it was still the best solution for my situation. I still get rubbing on the inner fender liners, but that was happening with the lower height and shorter tires too. You basically raise it to a level where you're comfortable with the amount of fender liner rub.

You may notice some of the extra "tippy-ness" during auto-x but my guess is that it won't materially alter the performance of the car.

 

Thanks for the replies, all! Sounds like it's not just the top of the liner/harness area that rubs. Good info.

Ended up pulling the trigger on some Hoosier A7's with 24.8" OD. Much better fit from the sound of it.

 

Why didn't you go with Toyo RR? Just curious... The Toyos last for many more heat cycles compared to the Hoosier with similar grip levels.

 

From what I read online the Toyo RR isn't a good choice for an autocross tire. Also got the impression it is more comparable to an R7 Hoosier.

 

Oh, autox. Gotcha.