Switch to Metric Tires

It's tire time for my bike and I've been looking at available sizes. This common question has generated some debate over in the KZ Forum. The same is probably true here, but I haven't found the thread (and I did search). Anyway, I thought I'd look for opinions from this group.

If a bike specifies 3.00-18 front and 3.50 rear tires and a person is looking for a more modern tread design, the options get pretty limited pretty fast. So, converting to metrics is an option. As I read the charts, the switch would be to 90/90-18 front and 100/90-18 rear. But options for those are also pretty limited.

The temptation is to jump a profile size to 100/90-18 front and 110/90-18 rear, both of which offer more options (such as the Shinko's that have been discussed here lately). Now the small twin guys at KZ Forum say two things about this: 1) It's not ideal in theory so don't do it, and 2) It works just fine in practice.

Does anyone here have an opinion to share?

A lot of tires have a spec for what wheel size to be used with. If my wheel is within their width range, I feel comfortable using the tire.

Del_Herring wrote: A lot of tires have a spec for what wheel size to be used with. If my wheel is within their width range, I feel comfortable using the tire.

The only company I've found that publishes those specs (at least on their Web page) is Dunlop.

Yea, I guess it's a little harder to find on bike tires, but it should be close between manufacturers. If you're oon the edge of their limits, I'd double check. But you should be able to contact them and ask. They'll know, most people just don't bother changing tire sizes very much, so they don't tend to hit the limits. I jump around tire sizes like crazy on cars, and have never had a problem. It may be worth considering changing the aspect ratio if you go wider, or you'll end up with a much taller tire as well, which might cause clearance issues. I always try to stay at about the same tire diameter, unless I'm intentionally doing it to "re-gear" the vehicle, and know I have clearance. I'd check and see if they offer those tires for other wheels of your diameter, that's at least a good starting point. I've never looked into whether motorcycle wheels are of consistant width, but aside from geneeral clearance issues, that's the real concern with changing tire sizes. Too wide or narrow, and they don't seat well, and you'll get roll on them, or worst case, lose seal and have a sudden flat.

mwriders wrote: The temptation is to jump a profile size to 100/90-18 front and 110/90-18 rear, both of which offer more options (such as the Shinko's that have been discussed here lately). Now the small twin guys at KZ Forum say two things about this: 1) It's not ideal in theory so don't do it, and 2) It works just fine in practice.

Does anyone here have an opinion to share?

I went up a size on the front because the tire was rotten and the bike shop only had that size...... the tire dragged on the front lip of my front fender. :laugh:

Had to elongate the mount holes enough to get it up a bit.

YMMV

[/quote]I went up a size on the front because the tire was rotten and the bike shop only had that size...... the tire dragged on the front lip of my front fender. :laugh:

Had to elongate the mount holes enough to get it up a bit.[/quote]

Never ran into that one, although I've made some significant ballpeen adjustments.