Tire size

sambo60

New Member
Dec 3, 2006
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California
I am looking to get new tires on my cobra. i have 10.5" wide wheels which have 245's on them. What would be the widest tire size i could get without it looking weird or having to do modifications to my car. Also what would be the best brand of tire for mostly street driving.
 
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Most tire manufactures list tire sizes for a range of rim widhts as approved by an organization called The Tire and Rim Association.

Some of the standards are listed below.

245/40R17 8.0 - 9.5
255/40R17 8.5 - 10.0
265/40R17 9.0 - 10.5
275/40R17 9.0 - 11.0

245/40R18 8.0 - 9.5
275/40R18 9.0 - 11.0
295/35R18 10.0 - 12

You can 'cheat' a little bit with little problems. Just wont get max performance.
I have run 275/40R17 on 8" rims for a couple of years even at track events.
 
You can easily stretch a 245 over a 10.5" wheel. I have done it before on a standard tire change machine with little issues at all. I don't recommend it as it exceeds the recommended width by 1.5". I have done a 195 over a 9" wheel before for a VW guy. They are stretched pretty good, but no issues at all. I have never had an issue with a stretched tire rolling of the rim during hard corning, but you do run the risk of making contact with the wheel which will cause damage.

A 275 on a 10.5" wheel works just fine. 275's are rated to fit up to 11" wheels with no problems. Of course they don't look as good as a 315/35. You can also go with a 285/40 which are just about 1/4" different in over all diameter and 1.4" in tread width between a 285 and a 315.
 
You can easily stretch a 245 over a 10.5" wheel. I have done it before on a standard tire change machine with little issues at all. I don't recommend it as it exceeds the recommended width by 1.5". I have done a 195 over a 9" wheel before for a VW guy. They are stretched pretty good, but no issues at all. I have never had an issue with a stretched tire rolling of the rim during hard corning, but you do run the risk of making contact with the wheel which will cause damage.

A 275 on a 10.5" wheel works just fine. 275's are rated to fit up to 11" wheels with no problems. Of course they don't look as good as a 315/35. You can also go with a 285/40 which are just about 1/4" different in over all diameter and 1.4" in tread width between a 285 and a 315.
Just because you can do it, doesn't mean it is safe. I would love pictures of a 245 on a 10.5" rim