Canadian Nissan Truck Club

K. since I'm new to this truck thing, one thing that I don't get is how to determine a tire size in inches. Honestly enough, I have a hard time with the regular sizing numbers. For what I think I'd read is that I can fit 32" tires on my stock X, which I was thinking of getting for when I get a set of winters and some off-road tires next year...but I don't thing you actually do to a tire shop and ask for a 32" tire, can you? I'm worried about buying a set and finding out after that they don't fit right

You can purchase most tires in either a metric size (like 285/75/15) or regular old inch sizes (31/10.5/15).

All depends on the kind of tire you want to get, and whether or not they make the size that you want.

You can also get equivalent sized tires in either measurment, ie. a 275/75/15 tire is approximately 31.1 inches around, otherwise known as a 31" tire that would fit on a 15 inch rim.

If you go into a tire shop and say that you want 32" winter tires, they should be able to find you something...

If I were you though, I would start with a 31" tire instead of a 32. You shouldn't have any fitment issues with a 31, whereas with a 32, you will likely have some rubbing issues with plastics in the wheel wells and mud flaps / splash guards.

32's would likely require you to at least do a poor man's lift (PML).

It is goofy, and typically not something you can easily do in your head, but here goes:

In the example of 285/75R15, the width is 285mm, sidewall height is 75% of the width (so about 214mm) and then of course they have to totally bugger things up by leaving the rim in inches, in this case 15. So to find the overall height, we take 214mm times 2, which is 428mm or 16.85 inches and add the rim size - 15 inches (rim), which gives you 31.85 inches, or about a 32.

Soooo, a 285/75R15 is about 32/11.2R15

Here you go
http://www.s-series.org/htm/calc/tiresizeconv.htm" onclick="window.open(this.href);return false;

then there is the good old tire companies that say the tire is a certain size when it is not it might be 265/70/17which is basically 32 or a little smaller but other companies same size is 32.5 so it is a hit and miss thing Most normal tire comps (goodyear,bfg,firestone) are pretty good for actual size though

[Tread Width in mm]/[Sidewall as % of tread width]R[Rim Size in inches]

Skinny is correct you calculate overall hight by converting the width to inches, multiply by sidewall %, multiply by 2 and add the rim diameter.

A good rule of thump is to find the tire you want or came stock, say 265/70R17, and to maintain the overall diameter any increase in width should have a corresponding decrease in profile or vice versa. So for our example a 275/65R17 or 255/85R17 would have a similiar diameter.

265/70R17 -->(265mm / 25.4mm/inch) * .70 * 2 + 17 inches = 31.6"
Wider 275/65R17 --> (275mm / 25.4mm/inch) * .65 * 2 + 17 inches = 31.1"
Narrower 255/75R17 --> (255mm / 25.4mm/inch) * .75 * 2 + 17 inches = 32.1"

Here is the tire calculator (http://www.1010tires.com/TireSizeCalculator.asp" onclick="window.open(this.href);return false;) I use to compare tire sizes. Saves you from having to do the math.