Lower profile tires to lower weight and increase gearing

[colecharris]

Hi, I have a 1.9l z3 w225/50x16 tires, the one size. I’m considering swapping with 205/45x16 tires. I can save 4lbs per corner from an already light tire, and increase gearing ~7%. But I can’t really picture it - will it look funny? Any other thoughts? I’m in a mission to save as much weight as possible and the gearing would help a little with acceleration. Thanks

[pbonsalb]

Tire brands and models vary in weight among sizes as well. Michelin PSS and PS4 and Conti EC Sport are lighter than most other tires in the same size.

As for gearing, yes, you can effectively alter final drive through rear tires. On my E90M3 I run 285/30/18 instead of 265/40/18 for about a 6.5% shortening. In my case it is like going from the stock 3.85 to a 4.10. I can feel the difference. The more rubber band like rear tires are noticeable to me but probably not to most people. Ride is slightly rougher in the rear.

Gearing helps with acceleration within the speed range of the gear you are in. Car could be faster or slower depending on whether the race was in a speed range that with your gearing provided more average horsepower and torque.

In my E36, I have run 3.15, 3.23, 3.38 and 3.64. I liked 3.64 except in long highway trips. By running a 255/40/17 rear tire, I effectively dropped the gearing to 3.57. It helped and the at really zinged through the gears to 143, which was redline in 5th.