Tire height question.

[A_USER_NAME]

Sitting around talking cars and a buddy of mine insists that a 225/45-18 on an 8" wide rim will be as tall as the same tire on a 7.5" wide rim. Reason the convo came ip is because I picked up these rims dirt cheap but they are 18x8 and 18x7.5. I know I can't run them unless the tire circumference is the same. But he insists the circumference will be the same.
With that being said wouldn't the overall tire height be slightly shorter on the 18x8?

Am I just missing something here?

 

[A_USER_NAME]

Hmm...well im picking up some 235/40's tomorrow and ill measure everything out for future reference.

 

[paul s]

The hight of the tire does not change with the wider rim. Its the aspect ration (45 in your case) that will change the hight. Your 235/40/18 will fit ( I have the same size), they call for 8" rim min.
http://www.1010tires.com/tiresizecalculator.asp?err=98&rsn=usr-snt-emty-str

 

[genegoesfast]

They should be the same height. The only variance would come from the tire being stretched a bit more on the wider wheel.

 

[1990AWD]

They should be the same height. The only variance would come from the tire being stretched a bit more on the wider wheel.

This. How much different though, I don't know.

 

[Jaxness]

They should be the same height. The only variance would come from the tire being stretched a bit more on the wider wheel.

Half an inch wouldn't be noticeable.

 

[A_USER_NAME]

They should be the same height. The only variance would come from the tire being stretched a bit more on the wider wheel.

This. Exactly my point, a tire that is stretched more will be shorter. As stated though I figured it wouldn't make much of a difference, if I wanter to I could add more air to the wider rim and im sure it would be close to the same. Thanks for the replies, just an odd though.