What Tire size should i get for 18 x 8.5 rims ?
 

Local tire shop said i should get 245/45 which would look like baloons ..His defense was that we have crappy roads and it would protect the rims. Whats the best size for bad street surfaces and bumpy roads .

245/45?! you sure he didn't mean 245/40?
 

245/45 is the wrong rolling diameter.

you *could* do 245/40 but 235/40 will look a lot better.

225-40-18 Y or Z rated

8.5 inches is 225mm why in god's name would he tell you to get tires that would stick out (more)
 

Trust me, I have stock 18x8.5 rims, and I have stock 225-40-18 tires. They fit just perfect and they look good. No problems with rim damage.

225 will look pretty stretched on an 8.5" wide rim ...
 

consider that audi uses 225 on 7.5" wide rims. 235 will look more natural imho.

no they don't.... that's what I have and it was stock

actually, 8.5 inches is 215.9mm.

what oem audi tt rim is 8.5" wide?

THIS is a 225-40-18 ContiSportContact2 on my stock 18x18.5 rims.... NO STRETCH!
 

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look at my post above....