Tire profile

Pardon me if this appears to be a stupid question. I have an 82 sc and have 55 profile tires on the front and 50's on the back. A lot of the wheel and tire combo's I see for sale have a higher profile tire on the fronts. Can anyone tell me why?

Toga82sc

You want the front and back to have the same diameter. The back tires are wider, therefore to have the same diameter as the front tires, they have to have a smaller profile.

Ex. 225*.50 =(about) 205*.55

The heigth of the sidewall is the same.
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Bill Krause
'79 911SC Euro


[This message has been edited by wckrause (edited 12-06-2000).]

Thanks, I was wondering.

Toga82sc

I think the German government passed a law in the early '70's about a spare tire having to be interchangeable with both front and rear tires if different sizes were fitted ... it was first applicable in '74 when the B.F. Goodrich 'collapsible' spare was offered, and on the Carrera, in particular, with it's 185/70 and 215/60 tires, with less than 0.1" difference in diameter!

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Warren Hall
1973 911S Targa

Remember, the "series" number is expressed as a percentage of tire width. So 50 series tires have a sidewall that is 50% of the tread width. The rear tires are wider, so thier sidewall (percentage of tread width) needs to be lower to make the car have a level rake.

-EJ