Tyre Placard Interpretations

[iwannabeapirate]

Hi All,
Potential stupid question here!

I am trying to figure out my tyre placard. It list both 7.50R16 and 10R15 tyres as approved.

My understanding is that a 7.50R16 should be approximately 31 inches in diameter (7.50 wide, 7.50 sidewall x 2 and 16 rim) even though they are more often around 32 inches.

Now if I used the same logic on a 10R15 that would work out to be approximately 35 inches in diameter. I can't see that Nissan would have ever fitted such a large tyre. I assume it means 31x10R15 but there is no mention of the 31.

Has anyone ever come across a tyre marked simply as a 10R15? If so, what was its diameter?

Cheers,
David

[Beastmavster]

Nope.

7.5R16 is a 32" tyre (31.8 really)

10R15 is a 31" tyre.

What you're confusing is that the 10R is that the R not the height but the width.

A 9R15 is a 30x9.5x15, a 10R is a 31x10.5x15, and 11R is a 32x11.5x15 and a 12R is a 33x12.5x15

Clear as mud.

At least metric sizes make more sense.

I think the 7.00R and 7.50R the R is fixed ratio in a more formal sense like you calculated.