: largest tire size with 20's?

03-12-11, 12:13 PM
right now im sitting on falken 245/30/20zr's but its getting close to that time for some new rubber. looks good and hugs the bends great, but i was wondering if i could run a larger sidewall to protect the rims a bit more and possibly get a little less reaction from beat up streets. i know a 35 will fit, but will it yield any negative effect? how about a 40? thanks for your time! any other suggestions are welcome as well...

03-12-11, 01:29 PM
First of all, I'd like to see pics of your Coupe DeVille.

275/35/20s here on the rear with 9.5 inch wheels, 255/35/20s 8.5 inch on front and no clearance issues. More rubber is better here I think. See rimsntires.com for fitment details. My rears have a slightly larger rolling diameter than the fronts and I have no ABS or stability problems. The stock wheels had the reverse situation, less rolling diameter in the rear. I have heard the computer will tolerate nearly 1.5 inch rolling diameter differences per axle, but I would stay conservative.

Finally, I think D3 does 10 inch width rims with 285s in the rear but am not sure of their aspect ratios though.

Keep in mind that if performance and ride quality is truly your goal it is expensive to exceed the factory wheels' capabilities. Unsprung weight is your real enemy for stopping and handling and a lot of larger wheels are heavier, couple that with less rubber and potholes kill!, We both know that though. Acceleration is also better on smaller not larger rolling diameter wheel/tire combinations.

All that said I love mine and they look great, but she is slower, less tossable and the city is dangerous with the summer wheels on. However, from a highway cruising perspective I am turning 3% less RPMs at actual highway speed equivalency and the ride is excellent.

03-12-11, 02:27 PM
thanks for your response. i'll try to gets some pics of the coupe deville on here for ya. nothing done to it at the moment, but i hope to restore in the next few years. but for now the body is in decent shape and the engine runs ok.

as for the sts, thats great to hear some feedback on tire size. i only rolled with the thinner sidewall because that was the closest to the factory size. if your clearing a 35 sidewall with no issues that helps sway my decision. hows the ride just cruising around? have you ever rolled on a 30?

03-14-11, 06:18 PM
Cruising around town is fine

03-21-11, 02:59 PM
I ran 295/35/20s and then tried 275/35/20 and they look horrible. went back to my 275/30/20 on my 10.5 in the rear and it looks great.

STS Serge 172
03-25-11, 06:17 PM
Anymore info on tire sizes on 20s for the sts???

03-27-11, 06:03 PM
how could you possibly need more info than what is posted here?

03-29-11, 12:27 AM
go to tirerack.com it help you