this is the tire size of the z400 20 x 10-9 radial
but looking through my magazine at some tires i wanna buy all i can find is 20x11x10 or 20x11x9... i dont understand any of these numbers except for the 20. can someone help me please

 

the second number is how wide it is and the third the rim size it will fit.

 

well, isnt the second how wide the tire And rim are?

 

the 20x11x9 will work because the tires on my 250R are 2 inches wider than stock and the 20 don't matter either because it's the diameter of the tire, the only one that matters it the last number. If your rims are 9 inch than make sure that the last number for tire sizes is 9. And one more thing just because i said that a tire with a little more width will work doesn't mean you should go buy something that is 3-4 inches wider to try to make it handle better because it won't a really wide tire will pop off the rim easier.

good luck

 

my brother n law has a blaster that had 21x10x8 on it and he ordered 20x11x8 tires and they worked fine

 

ok i get it so the first number is the actual tire size right? dumb question i kno...

 

The only important number that you have to worry about is the last number. That is the wheel size. Everything else is purely preference whether or not you want a tall/short, or narrow/wide tire. Most people think you have to put the exact size back on, but you dont. Basically any tire with the right wheel size will technically work.
Anyways, if anyone is still unclear about what the number means, it goes like this, and I will use an example.
22X11X10
22=tire height, or diameter
11=tire width
10=wheel size

 

NichelsonRacing87
What you said, was pretty much correct as well.

 

the 4x4 machines are where it is more critical when changing tire sizes (again, the first number is what matters here). As it was mentioned many times earlier, the last number is your rim diameter. This must match the tires that you are replacing unless you are adding aftermarket rims as well and changing your rim size.

 

On a 4X4 all you have to do is make sure that all four new tires are the same size, you can put bigger(or smaller) tires on if you want.