Bike tires today come in more sizes than one can count, so buying tires can be problematic when it comes to tire with.

Tire width is expressed two ways, inches and millimeters. Inches is the standard labeling on most MTB tires (IE: 29×2.4), ETRTO is the metric size in millimeters (IE: 61-622).

Very simple yet deceptive because the two seldomly match, and that can cause the bike to prefom poorly, especially in high speed cornnering.

This happened again to me recently that two of the same tires (29×2.4 maxxis dissector) had different tread widths.

Originally I set up with two Maxxis dissector tires front and rear, same compound(3C MaxTera EXO) same size. Because the rear tire was wearing harder on the side lugs I decided to go with a dual compound(DC) in the rear.

Never thought twice just threw it on and started riding. I noticed my cornering was not as smooth but thought it was me. This season I bought a new bike put the same tires on and had the same problems cornering, again just thought it was me.

As I was relacing the fron wheel with a wider rim and noticed that the rear tire still looked bigger even though it was on a narrower rim. Upon measuring I found that the DC was 1.25 mm or so larger, about 0.050′. Doesn’t seem like much but it is enough to cause the rear of the bike to track to the inside during cornnering, most noticeably at higher speeds.

In measuring several tires I have on hand I find that the stated size on the tire is seldomly accurate.

Maxxis Dissector: 29×2.4 (ETRTO 61-622) 3C MaxTera is actually 2.465 inches & 62.6 mm.

Maxxis Dissector: 29×2.4 (ETRTO 61-622) dual compound is actually 2.525 inches & 64.1 mm.

Schwalbe RockRazor 29×2.35 (ETRTO 60-622) Evo Addix speed is actually 2.4 inches and 61mm.

The point: is when setting up two different tires or compounds on your bike, pay attention to actual size of each tire and make sure the rear doesn’t oversize the front.