Real tyre sizes.

[M1S3RY]

<rant>

My question to all is why have a certain size listed on a companies web site, and on the actual tyre, when they are not the actual size. My case example, i just bought 5 31x10.5x15 Bridgestone Desert Duellers (604v) which are supposed to be 31 inches tall, but when i measure them, they are only 30 inches tall. Now am i missing something here or should i have expected this? I know making a tyre to the exact millimeter would be difficult, but the be out by 25mm would this not constitute false advitising. Can anyone shed any light on this?

</rant>

[Slunnie]

Not sure.

My Simex JT2's marked as 34x11.5-16 measure 35.2x12

[Ryano]

The manufacturers are allowed a + or - 2% variance on their designated specs and are also able to work within a band to be able to label it as a certain size....
So say their tyre is towards the lower end of the band and then they have a -2% variance on their specs... this leads to a big difference.
Different manufacturers work to different specs in different sizes.... work out the size you want and then have a look at each of the brands in that size. You'll get a more accurate perspective on it then.

[DFND90]

Were the tyres mounted when you measured them? Might make a small difference??

My 34" jungle trekkers measure 35", same as slunnie.

I think its always good practice to advertise the tyre size slightly less than actual so the customer is always pleased. Like Simex.
You always feel ripped if your tyre is less than specified.

[M1S3RY]

I measured it off the spare, i wans't looking to trouble the manufacturer, i just wanted to know why this would be.

[DFND90]

just wanted to know why this would be.

So they can sell you 30"s of rubber @ a 31" price

[Big Red Toy]

also depends if its on a rim or not when its measured & also what width rim also affects it.
My 36 swampers measure 36.2 on 8 inch rims at 35psi, but if i drop the pressure they will shrink so also depends on what pressure u do your measuring at

[crankycruiser]

A mate of mine bought a set of 33" Maxxis Buckshots and they only measure 31"... needless to say hes not happy.........................

I had a set of 35" Maxxis mudzillas and they were only just a 34"

[r0ck_m0nkey]

I don't know why any of this is a surprise. Take a look at the tyre specifications found on a lot of tyre manufacturers websites and most of them clearly display that the sizes are smaller then the labelled size.

[M1S3RY]

They are on 15x7 inch rims @ 40 psi