[timyoyo104]

my car is 225 40 18 front. and 245 35 18 back.
if I go square with stock rim. what's the best size.
my thoughts is 235 40 18 .
any advise?

[BEM-S4]

Post should be in wheels and tires sections you will get better responses.

[albertw]

The "best size" depends on what you want out of the car.

1. If you want maximum acceleration from very low speeds, the widest, stickiest rear tires are what you need, especially if you don't want to buy a limited slip differential.

2. If you want to run twisty roads fast but don't ever want to cope with a slide, you want the widest, stickiest tires front and rear.

3. If you want you run twisty roads fast and enjoy playing with the traction limit, 225s with the standard Pirelli all seasons are excellent. You get to the traction limit at lower speeds than with wider, stickier tires, and the car is beautifully balanced at the limit. You have plenty of traction for the typical twisty road full power pass starting at 90 km/hr, but forget about hooligan-style stoplight drag races.

[timyoyo104]

thanks. i just need tire that for daily drive with comfort. no track or twisty road.
think getting set of mps a/s 3

[hwntime]

I'm curious too. Front offset is 45 and rear is 52 on the staggered setup if I'm not mistaken, so given the wider wheel up front, what would the best spacer size be for balance?

[albertw]

Originally Posted by timyoyo104

thanks. i just need tire that for daily drive with comfort. no track or twisty road.
think getting set of mps a/s 3

The a/s 3 is an excellent tire. Stickier than most all season tires, long wearing and not unusually noisy. About the only negative (on my previous Z06) was a rather abrupt break-away, but that's not an issue for you.

Why do you want to go square? Any time you depart from the stock tire sizes you run the risk of confusing the safety nannies. It doesn't matter how many posts you see claiming "no problems", unless you have a clear statement from BMW that your setup is approved, you can never be sure.

I ordered my car with all seasons to get the square set-up, which I expected to reduce understeer (it does) as well as the safety nanny issue. I expected to ditch the Pirelli runflat A/S tires immediately based on all the negative comments, only to find that for my needs (#3 above) they are excellent.

You do get the ability to rotate the tires, but for a rear wheel drive I don't see the point. If you have uneven wear side-to-side you have an alignment problem. If you have uneven wear centre-to-side you have a tire pressure problem. Better to fix the problem than to mask it by rotating the tires.