Tire Question

[Anakonda69]

my buddy has a '99 audi a8. he wants some 19" rims. what size tire would fit on there? right now he has 225/55/17's. he said on tire rack they said 255/40/19 but i think thats too big. any ideas?

[JohnnyT]

Generally Tirerack is conservative in the tire sizes they quote. If they said that size would fit, I would imagine that it would.

[jbiscuit]

call them directly and ask them....or contact marty at Big Bear Tire. He surely can help.

[Anakonda69]

well my friend runs pomps tire here in new berlin and he said there is no way that tire is fitting under an audi

[Anakonda69]

thats a 27" tire

[JohnnyT]

Based on the calulations I just did, the 225/55/17 is a 26.7" tire.

Width x Aspect Ratio = Section Height
Section Height x 2 = Combined Section Height
Combined Section Height + Wheel Diameter = Tire Diameter

225/55R17

225mm x .55=123.75mm
123.75mm x 2=247.5mm
247.5mm + 431.8mm(17")= 679.3mm or 26.74"

[Anakonda69]

so then the 255/40/19 it only like .4" bigger...which would be roughly 27" guess i didn't think his tires were that big

[JohnnyT]

You have to remember a change from a 55% aspect ratio to a 40% is pretty drastic. It's the old size +1 rule...

[Anakonda69]

maybe thats why my friend told me he didn't think it would fit...not to mention the tires in that size are expensive

[Car Guy]

http://www.discounttiredirect.com/direct/assignTireVehicle.do?yr=1999&vid=000507

Look at one of the 'options' for the stock 17" size......it's a 255 tire.....

[Al]

My old man has the 18" tires on his S4.

FAIR WARNING!!!
The ride will suck after the change. Every time you hit even the smallest crack in the road, you will feel a sudden jolt as well as hear a sound similar to a good whack with a hammer to the frame. I think the tires on an A8 are a bit bigger, but I would expect similar results.

Overall; BAD IDEA

[Slow Joe]

I went from 16" Wheels to 18" wheels on my Mustang at one point... It depends on what you're trying to do... When you have proper width tires with proper inflation in each, comparitive the 16" rim will ride softer because of increased sidewall... The 18" rim will provide a more harsh ride, but improve handling. I've never "[felt] a sudden jolt [or heard] a sound similar to a good whack with a hammer to the frame" at any point in having the 18" aftermarket wheels on my car, except when I bent two of them all I felt was the jolt, nothing else, no noise... Oh and as well, I can think of many cars with STOCK 18" and larger rims that don't do that either... So I'm not sure what to say about your dad's car... That's just strange from what I've dealt with...

I'd say if he's looking for ride quality, keep the stock wheels... If he's looking for handling go with bigger rims with low profile tires... Also look at some suspension upgrades at that point as well...

[GHOSST]

Just get em, if they dont fit, make em fit! j/k.