Reading a size
27x9R12
- 27 Overall diameter
- Nominal, approximate overall tire diameter in inches.
- 9 Section width
- Nominal, approximate section width in inches.
- R Radial
- R means radial construction.
- 12 Rim diameter
- Wheel or rim diameter in inches.
Write the size down exactly the way it's printed on the sidewall, punctuation and all. The marks between the numbers are part of the size, not formatting.
R, dash, or x
The mark between the width and the rim diameter is what tells you the construction.
27x9R12
Radial
The R between the width and the rim diameter means the tire is a radial.
27x9-12
Bias-ply
A dash is the usual bias-ply notation. Some brands write it with a decimal width, like 27x9.00-12.
27x9x12
Not stated
An x here doesn't say how the tire is built. Check the tire or manufacturer specifications instead of guessing.
Vendors don't all write sizes the same way. Maxxis lists the Bighorn radial as AT27X9R12 and the bias-ply Workzone as 27X9.00-12, and both are correct for those tires. Don't convert a dash to an R or an R to a dash when you order.
Radial vs bias-ply
The same nominal dimensions can exist in both constructions — 27x9R12 and 27x9-12 are two different tires that measure about the same. Neither one is better across the board; they behave differently.
Radial
A more flexible carcass. Generally a softer ride and a flatter footprint on the ground.
Bias-ply
Generally a stiffer sidewall, and common on utility and rough-use ATV tires.
If your size doesn't say which one it is, ask us or check the manufacturer specs before you order.
Where to find the size
- Tire sidewall — the molded numbers on the side of the tire.
- Tire-information label or owner's manual — often on the frame, under the seat or in the manual.
- Shop by Machine — pick your year, make and model on our site when fitment is available for your machine.
Check both front and rear
Many ATVs and UTVs run a narrower front tire and a wider rear tire, so write down both sizes before you shop.
Front
27x9R12
Rear
27x11R12
Don't assume the tires on it are factory size
A previous owner may have changed sizes. If you want to replace what's on the machine now, use the size molded into those tires. If you want to go back to the original size, check the manufacturer specifications or call the shop and we'll look it up with you.
Use the printed size, not a tape measure
Tire size numbers are nominal. Mounted dimensions vary with tire model and construction, rim width, air pressure and load, so a tape measure can read a half inch off. Go by the molded size whenever you can.
Still not sure?
Send us a clear photo of the tire-size marking on your front and rear tires and we'll help identify what you need.