MTB Tyre sizes

[Eugene]

What does the 1.95, 2.1, 2.25 etc reading on a MTB tyre mean?

 

I always thought that it was the width of the tyre. Now from what I've read it could mean the height of the tyre. Google says it is the circumferance of the tyre in meters.

[madbradd]

Definitely not circumference as you get a 2.2 in 650B, 29 and 26 inch wheel sizes. Then your height and width of tyre will be proportional as the tyre has a nearly round section unlike a car which has a more rectangular section - not sure if that makes sense. So you will find a 2.2 has more volume or height AND more width than a 2.1

[Captain Fastbastard Mayhem]

It's the same as car tires. Generally refers to the width of the tire itself, although much like different clothing manufacturers measure waist circumference differently, different tyre manufacturers have different ways of measuring width - either the external width of the casing, the width of the tread on the tire or the internal width of the casing.

 

Which is why a schwalbe 2.35 is often the same "size" as a maxxis 2.5, although lately they seem to be following the same conventions in sizing. Mostly.

[Captain Fastbastard Mayhem]

Oh btw - on car tires, the first number (195/205/225 whatever) refers to the width of the tire. The second number (35/45/55/65) refers to the sidewall height, and it is expressed as a percentage of the tire's width.

 

So a 200/55 tire would be 200mm wide and 110mm tall at the sidewall (200mm x 55%)