Pete @ Stratmosphere

so that means your sidewall is then further reduced from the 18's that you run. So, your risk of tire and wheel damage are definitely increased. I am hesitating to stock 19's for that reason for the Audi cars. For something like Porsche in the rear where the sidewall is still massive on a 19 application, that's a different story. -Pete

ruknd

and add that 18s generally have less rotating mass than 19s

Pete @ Stratmosphere

Right. The new RS 4 is coming with 19's but the tire width is increased.

b-thumper

Ride height should not change when you change wheel diameter because your total rolling diameter (edge of tire to edge of tire) is the same.

For example, an 17" rim with a 225/45/17 tire will be 25" in diameter.

If you upgrade to 19" rim, you would run 245/30/19 (if it fit under your fenders) and the diameter would be 24.8" (basically 25")

Any time you upgrade rim size, you want overall diameter to be <b>the same</b> so that your speedo stays the same. To do this, the sidewalls get thinner when you up in rim size.

<b>Repeat after me, rolling diameter is the same regardless of rim diameter</b>

The only reason the car "looks higher" when you go to 19" rims is because the offset is usually much more agressive on an aftermarket rim (and makes the wheel gap more apparent). That said, your wheel gap size <b>does not change</b> when you go to a bigger rim<ul><li><a href="http://www.miata.net/garage/tirecalc.html">http://www.miata.net/garage/tirecalc.html</a</li></ul>

S4AVNT

By "width" do you mean outside diameter?