New tires - same size front / rear or not?

[bkirk]

I'm about to go out and have four new tires installed on my 1999 Z3 Coupe. I know that stock there are two different sized tires on the vehicle, but wonder about the sanity of using the same size (the size of the rear tires) on all four corners. Has anyone ever done this without any other body or suspension modification? The result? Any reason why I should consider this, other than the obvious one that BMW didn't intend that to be done.

[BimmerBreaker]

What you are describing is running a "square" setup. It is very common, but you should swap wheels so the rims are the same width front and rear if you want to run the same width tires front and rear.

[bkirk]

What you are describing is running a "square" setup. It is very common, but you should swap wheels so the rims are the same width front and rear if you want to run the same width tires front and rear.

Thanks for the quick reply. I hadn't even thought of the rims being different widths.

[s8ilver]

Meh, to some extent you can run same size tires on staggered wheels, but that defeats the purpose of rotating tires. My Coupe came on staggered 7.5" & 8.5" Style 68s and 225/45-17 all seasons all around and it felt just fine...handled quite well actually. What I didn't know at the time was that the wheels were staggered until I replaced tires and tire shop couldn't get a wheel to fit up front. I went out and stared at it and then noticed two of the wheels were 8.5" wide.

I do run four 17x7.5 DSII on 225/45 Blizzaks in the winter, and just run a wider spacer out back (12mm F, 20mm R) and it at least looks normal.

I'll finally get it right this spring though. Staggered Style 42s (Z3 fitment) with those same spacers and correct rear rubber (thinking 255) and I think I'll finally have it looking and handling the way it really should. I'm sick of lighting up the ASC light in 3rd on the snow tires. Great in the snow, very limiting in the dry.