Tire sizing??

**Quicksilver_GP** · 04-25-2008

Okay, what tha hell? Im lost.... All these tire sizes and numbers, im no gearhead like some of the veterans of our fine forum, so help me out fellas. I believe that i am running 225 60R16's on my GP currently, stock 16 inch 5 spoke rims. My question/confusion is...what do these numbers represent? The only part I know is that the "R16" represents the rim size, but what does the other stuff mean? One of them is obviously sidewall height, is the other one the width of the tire? For instance, I see some guys on here mention that they're running 245 60R18's. Why not 225? Can I get better tires than the size I am currently running, or does tire size not really have as much to do with handling as the quality of the tire does?

**Sabrewings** · 04-25-2008

225 -> width of the tread in mm.
60 -> thickness of the sidewall, as a percentage of the tread width (in this case 60% of 225mm)
R -> radial tire
16 -> rim size in inches

If someone is running 245/60/18s their speedometer is way off. Should be more like 245/45/18s to keep the rolling diameter the same. Use this to compare tire sizes:

Tire size calculator

They are using 245s because the larger rim is wider and requires a wider tread.

**Quicksilver_GP** · 04-25-2008

Sabre, Ive siad it before and Ill say it again: u, sir, are bad@$$. Thanks a bunch man! So, in other words, there's no way to increase the tread width without screwing up the speedometer or going with a bigger rim?

**Sabrewings** · 04-25-2008

You can increase the tread width as wide as your rim (and suspension components) will allow. Just make sure you drop the sidewall percentage number to keep the tire's size (actual height or rolling diameter) the same so the speedometer will read the same.

The calculator I linked to will help you find the right tire size. Put in your stock size on the left, then play with the numbers until you get one that's near the size of your stock tire. That way you never have to worry about tire size problems.