Quote:
Originally Posted by scdroptop
I have 245/35/20 in the front...285/30/20 in the rear and have no problems rubbing (not lowered), no difference in acceleration and car drives 300% smoother than RFT's I just took off with stock wheels. Fuel economy the same.
I think every wheel/tire combination is different, along with driving habits, frequency, climate, road conditions. It's very hard to compare all these scenarios, unless of course you do a meta-analysis. 
BTW-checked with Discount Tire, Tire Rack and the company that sold me the wheels and they all said 245/35/20 was the proper +2 size in the front (or at least one of the proper alternatives). I specifically asked each one if there would be a speedo difference and they said not. Not sure, but it "feels" right...much smoother than my 19's and 18's on previous SC's and this one. |
This from the tire spec from Falken for the Fk452 (one of the few tires that make such small sizes)
http://www.falkentire.com/Tires/Passenger-Car/FK452-3
A stock 245/40/18 has an Outside Diamter of about 25.7
A 245/35/20 is 26.7
A 245/30/20 is 25.8
(which will give you ~4% error on the speedometer and milage)
When I had my 245/35/20s, things were pretty good till I lowered the car and I started rubbing the top of fenders as well as the inside and outside while turning.
So as long as you don't go super low, you should be ok. But even if slight, there will be loss of performance and true your milage my go up.. but my whole point is that there are reasons to not go 20s vs 19s other than looks and if you have to run your car higher, then the 20s are for nothing.. (IMHO).