Breakdown of Tire Sizes

[Smigjo]

So can someone help me out with this? I've been getting mixed messages from multiple people about what each number means. For example I'm talking about 335/95/18. I know 18 is rim size. Oh, and rims, 18x10 means 18 inches tall and 10 wide correct? Back to tires, 335 would be height in millimeters correct? What about 95? I've heard that's like a ratio of the tire to the wheel or something. Thanks for any help

 

[det_riot]

you are correct on the rims. an 18x10 rim means 18" in diameter and 10" wide.
as far as the tire size, you're very confused.

For purpose of explaining we'll use the tire size 335/30/18

the first number is the width in mm.
the tread is 335mm wide.

the second number is a ratio of tread width to sidewall height. so the sidewall is going to be 30% of the width. 30% of 335.
335 x .30 = 100.5mm
so the sidewall of the tire is going to be 100.5mm

the third number is the inner diameter of the tire, aka the rim diameter.

 

[ProKiller]

the first number is the width of the tread. the second number is the percentage of sidewall as related to the width. the last number is the rim diameter. and yes 18x10 means, 18'' round and 10" wide.

Your example is a little ridiculous. that means the width is 335 millimeters with a sidewall height of 318.25 millimeters. that's like an offroad mudder.

 

[det_riot]

pretty sure that his example was bigger than an offroad mudder lol

 

[95PGTTech]

the second number is called the "aspect ratio" and as the others have explained is the ratio of the width of the tire versus the sidewall height. effectively, it's a general ballpark on tire height, or how "tall" a tire is. a common mustang size is 275/45/17. a 275/50/17 would be a bit "taller".

 

[Smigjo]

Bahaha ok I got it now, thanks. That is a huge tire, that's like one of those tractor tires that go on the tractors that are made to go inbetween the rows of crop.