Tire size?

[Anonymous]

I've never bought motorcycle tires before. Can somebody please explain what all the different numbers mean (ex. 120/90H - 19). I understand that the last number is the wheel size and the Letter is the speed rating, but what do the other numbers mean?

Thanks

[JJ]

In the example size that you used, the "120" is the cross-section width (widest part of the tire when inflated to the recommended pressure, NOT the tread width) of the tire, in millimeters. The "90" is the aspect ratio. That is, the height from the rim to the outside edge is 90% of the cross-section width( in this case, 108 millimeters).

[Anonymous]

JJ if this is correct, the tire size should change, depending on wheel width. The tire, at it's widest point would be wider mounted on a 3.25 rim than it would be if mounted on a 2.75 rim

[JJ]

That is true. The advertised cross-section width is dependent on the wheel width. The size shown on the tire are for the manufacturers recommended wheel width, whatever that may be.

[earlfor]

Tires are made for specific rim widths. It would be a very bad idea to mount a wide tire made for a 3 or 4 inch rim on a narrow 2.5 inch rim and just as bad an idea to put a narrow tire made for a 2.5 inch rim on a wide rim. Unless of course the intent is to throw the tire off and do some hot dog rim riding. :-) :-) :-)

Earl

JJ if this is correct, the tire size should change, depending on wheel width. The tire, at it's widest point would be wider mounted on a 3.25 rim than it would be if mounted on a 2.75 rim

[Anonymous]

Is the rim size on the tire markings? I thought I'd read all the writeing on many tires, but I don't remember seing a spicific rim width printed on the tire. Or have I just forgot?

[JJ]

The recommended wheel width is very rarely, if ever, shown on the tire. You have to check with the dealer, who should have that info in the manufacturer's catalog, or try the tire manufacturer's website. If you stick with the motorcycle's recommended stock tire sizes, on the original wheels, there won't be any problems.

[saaz]

Try the Continenetal tyres site in the UK. They have a good tech area for ll the info on tyres specs