Topic: Going to wider rear rim/tire on a cb500

[gregwaits]

What all is involved in going to a wider rim and tire on a CB500? What is the limit on larger size? Must one change out the swingarm? What other problems would a person encounter if they were to try this?

[nickjtc]

This general topic has been covered in other threads, with the usual feeling being:

If you mount a tyre on the stock rim which is not per OEM specifications you risk upsetting the handling of the bike, and the way that particular tyre will perform on a rim it is not meant for.
There will almost certainly be clearance problems with the swingarm unless you keep the size difference modest...in which case, why bother?
If you go the custom route and fit a new swingarm with greater clearance for a wider tyre you then may have problems with the alignment of the front and rear sprockets.

Hold on for replies from others who may have a different insight into this.

[FunJimmy]

Can't say I know yet, but I picked up a WM5 - 3”x 18” DID alloy rim for the rear and plan on spooning on a 130/80-18 Bridgestone BT45. Up front it’ll be the WM4 – 2.5 x 19” Excel rim also from ebay with 100/90-19 Bridgestone BT45. These sizes will fit and not look like the bike is trying to be something it’s not.

Just how big are you thinking?

[cafe75-550]

I know that a 120/90 will fit just fine, as well as the 2.5" rim to go with it, as I have these on my 550 with plenty of room to spare.

 A 130/80 on a 3" rim would be no problem at all. After that the brake stay is going too be the first thing that gets in the way, but this could be modified for additional clearance without much difficulty.

I believe that a 140 or 150 series tire could be done with a little modification to the brake stay, without any swingarm problems at all. After that though you're going to be getting awfully close to the chain and the swingarm.

[hymodyne]

its been covered, but
its not just about what will "fit" the swingarm any more than it is how large an engine I can squeeze into my frame (He says this with an overbore kit installed )

tire footprint and wear characteristics are factors as well.

hym

[Ricisan]

I have a WM 3 rear w/130/80/18 and WM 2 front w/100/80/18. The rear is fine the front has to be manuvered in carefully to get disks into calipers.
Working on rearsets now, then rear brake lever.