Tire size help! ordering asap

[peetacheeta]

Hey i know there are a ton of questions about tire sizes as we all probably get a little nervous before we order hoping we have the sizes right.
The bike is a 75 xs500. It has a 4.00 x 18 rear wheel.
Everywhere i check online it says to run 110/90 x 18
My 77' xs650 has a 4.00 x 16 rear and it has a 130/90 x 16 tire and my 83' Virago runs the same rear tire.
I;m just confusing myself
what should i get? 110/90, 120/90 or 130/90(can it be this wide)

thanks!

 

[5twins]

110/90 is correct

 

[peetacheeta]

is it ok to run 120 or 130? what is the downfall and why would they be on my other bikes then?

 

[jamesgs4]

the other bikes are 16" wheels, and the 130mm part of the tire is closer to the center of the wheel. if you run a 130mm-18 inch tire, it might be too wide.

 

[turn left]

110, 120, & 130 refer to metric sectional widths in mm. Approximate translation is 110mm=4.3inches, 120mm=4.7inches, 130mm=5.1inches. So if you have a 4" wide wheel go with a 110mm wide tire. Any larger will pull the sidewalls in too far and cause a ballooning effect thus putting less actual surface area on the ground. Abnormally fast wear in the center of the tire would also result from going too large (saw this a lot at my old shop). The 18in diameter rim size is irrelevant to the width decision but does factor into choosing tire height which is that slash /90 (%) measurement.

 

[5twins]

Your bike will ride and handle best if you use the stock size. If you don't care about that and are only concerned with looks, stick anything you want on there.

 

[jamesgs4]

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[turn left]

Jamesgs4 has a valid point about rubbing issues when going wider. I think we (mostly me) overloaded this thread with info. Peetacheeta, the first reply is the best answer

110/90 is correct

 

[bluebikerblan]

Jamesgs4 has a valid point about rubbing issues when going wider. I think we (mostly me) overloaded this thread with info. Peetacheeta, the first reply is the best answer

Yup and Yup

 

[peetacheeta]

i know 110/90 18 is correct but it just seems too thin. i am running a 21' wheel (80/90 21) on the front so handling isnt going to be that great anyways.
I guess i'll live with the 110. i am mounting them myself so these are probably easiest as well.

thanks for the responses guys
appreciate it