I just mounted a new set of tires/wheels: 235/45/17 ZR Michelin Pilot Sports on 17x8 SSR GT1s. This set replaces my old set: 225/50/16 ZR Michelin XGT-Z4s on 16x7.5 O-Z Monte Carlos. The old 225s are *wider* than the new 235s! What gives?

 

How could that be possible? What makes it seem that the 225's were wider than the 235's? Does it look "wider" compared to the fender? Maybe it's because your old rims' offset is different from your new rims' offset.

 

The same thing happened to me, I wanted 235/40-18's but they were narrower than the stock 215/55-16, so I decided on 185/70-14, which turned out to be the widest!

j/k what you say is not possible as 235 is the width of the tire in mm

 

Hey Bullseye gotta be a glitch between manufacturers cuz according to the specs I work with they are close but the 235's are a bit bigger.

 

that makes no sense my old 17's had 225 and looked tiny compared to my new 235's on my 18's.

Ant

 

it's possible. there's a certain amount of discrepancy between different tire manufactures. for example when we compared the width of 235/45/17 Road Huggers and 235/45/17 Nitto 555s with the tires/wheels off of the car - the Nitto 555's were almost a full inch wider than the Road Huggers - in the supposedly same size. in fact those Road Huggers were even slightly smaller(width) than my 225/50/16 Yokohama S306s when compared side to side. i guess not every manufacturer uses the same ruler.

 

The measurement of the width I believe is the maximum width and not the tread width, some tires have a wider sidewall than the tread.

 

The old 225s are Michelin Pilots. The new 235s are Michelin Pilots. What makes me think the old 225s are wider than the new 235s? Taking an old wheel/tire off the car and putting it next to a new wheel/tire for the express purpose of comparison. The old 225 is obviously wider than the new 235, about 1/2-inch. Will the new 235 tires become wider with wear? I am baffled...

 

maybe different air pressure? or since the old ones had just come off the car they may have been "flattened" a little since they just had 3000 pounds sitting on them.

 

I was just thinking the same thing. There's no way 225/50/16s mounted on 16x7.5 rims should be wider than 235/45/17s mounted on 17x8 rims. But they are. I'm thinking my new, "wider" set-up will get that way once the car has been rolling on them a while. I hope so...

 

I get a kick comparing tread width of different tires from the same manufacturer on TireRack. Some real discrepancies. You said both your tires are Pilots, but there are different levels of Pilot tire. Unless they are the exact same model, could be the difference. Check the specs online .... hey, this is interesting! I just did the search and though tread width is unavailable, sectional width is almost identical for 225/50-16 as for 235/45-17 in Pilot Sports!
http://www.tirerack.com/tires/Spec.j...el=Pilot+Sport

 

Are we talking section width here or tread width?

Section width is the width of the body of the tire and should be close to the number on the sidewall in mm. Tread width varies even more widely depending on tire design, so two same size tires can have very different tread widths. Tires also can end up wider or narrower depending on how they hang on a given rim width in a certain size (I think).

 

Yeah, you're right. Tires will stretch over a rim and sidewalls will shrink. Were the rims the same??