90/90 18 inch tyre instead of 90/100 18 inch.

[Next edition]

Krasi is right, In this case the tire profile height will be higher if you go from a 90/90 18 inch tyre instead of 90/100 18 inch, meaning it could rub on your fender, width an rim size are the same. Only go different from stock if it has been an commonly proven modification, it could screw up your handling, although going bigger is usually better thought of than going smaller.



The width is the first number, and to a point they'll fit physically as long as they are within about 20mm, for example a 70mm or 110mm tire would probably fit on a rim designed for a 90mm tire. Although I wouldn't recommend anything other than the tire size that comes stock. It doesn't matter on the brand of the bike or the tire, they should all be the same dimensions.

the first number is the tread width right but what about the rim width,like on some car rims have a 6.5inch wide 18 inch rim and then you can get a 7.5 inch wide 18.