Originally Posted by

**CerOf**

A 305/65R17 is about the same size as a 285/70R17. It is about 2/10th" smaller. The wide increases to 12" though with a 305. This makes a HUGE!!! difference in the size of the tread blocks and the size of the voids. The larger tread blocks and larger voids make it MUCH better off-road.

I've run 235, 245, 255, 265, and now 305 section width tires and by far, the 305 width wins hands down for off-road performance.

As a general rule, the second number will always be a multiple of "5." For each increment of "5" you go up, you gain almost an inch. For each increment of "5" you go down, you lose almost an inch.

the same is true for the section width but based upon increments of 10. Assuming the aspect ratio stays the same, for each increase of 10mm in the width, you gain almost an 1" in height.

285/75R17 is essentially a 34" tire

285/70R17 is essentially a 33" tire

285/65R17 is essentially a 32" tire

305/65R17 is essentially a 33" tire

305/70R17 is essentially a 34" tire

305/75R17 is essentially a 35" tire

285/75R16 is essentially a 32" tire

295/75R16 is essentially a 33" tire

305/75R16 is essentially a 34" tire

so on and so forth. You can see the pattern and apply it accordingly. Real world numbers do vary slightly, so only use this as a general rule.