Metric Tire Sizing Help

[French_Bulldog]

Hey,

I hate to do this to you guys, but I need help figuring out what the biggest metric-size tire I can fit on my stock ‘98 4-banger is. I’ve read that 31” is the max diameter a stock tire can go with no rubbing - is this correct? And if so what’s the metric equivalent of a 31” tire? (I wish they’d just give us the diameter in cm, and not the stupid “aspect ratio”)

I want to be able to off-road and have full turning range without rubbing - I’d love to fit something bigger than the 28s I’ve got right now.

My issue is that the metric tire sizing is incredibly confusing since the overall tire diameter is not given. Does anyone know what size I need?

Thanks!

 

[Ocho]

Hey,

I hate to do this to you guys, but I need help figuring out what the biggest metric-size tire I can fit on my stock ‘98 4-banger is. I’ve read that 31” is the max diameter a stock tire can go with no rubbing - is this correct? And if so what’s the metric equivalent of a 31” tire? (I wish they’d just give us the diameter in cm, and not the stupid “aspect ratio”)

I want to be able to off-road and have full turning range without rubbing - I’d love to fit something bigger than the 28s I’ve got right now.

My issue is that the metric tire sizing is incredibly confusing since the overall tire diameter is not given. Does anyone know what size I need?

Thanks!

don't know what size you need but this has worked well for me in the past for sizing of metric tires:

https://tiresize.com/tiresizes/

 

[97' 4 Popper]

https://tiresize.com/calculator/

265/75/15 seems to be the equivalent to a 31/10.5/15.

 

[Mike_H]

You can calculate the diameter from the numbers.

the first three digits are the section width so a 255 section width means the tire is 255 mm wide (or about 10 inches). The second set of numbers is the aspect ratio, and that is the percent of section width to sidewall. So, a 255/75 means the sidewall is 75 percent of the section width (255*.7 = 191.25). The last number is the wheel size the tire is designed to fit on...so a 17 means the tire fits on a 17" wheel. To get diameter, you take the sidewall, multiply it by two, then add the wheel diameter.

Our 255/75R17 tire used in the example is 10 inches wide, and each sidewall is 191.25mm or 7.5" tall. Double that (15) because its on both sides of the wheel and then add 17 for the wheel size. The flotation number for that tire would be a 32 x 10 x 17

Note: I use this tire as an example because its the factory size for JK Rubicons that people seem keen on fitting.