Swell tyre?

Q: Hello folks and I was wondering if you could help or direct me to the path of truth regarding differing tyre sizes on a motorbike?

It seems like everyone likes to put an oversize tyre, especially on the rear, on their bike. There’s no doubt that they look the part from behind, unlike myself, but I’d like to know what adverse affect they’ll have if one does so?

So that’s my question here. Is it wise or maybe even stupid to fit a tyre that’s too big, according to the manufacturer, or does it not really matter?

Corbus

A: It does matter, a lot, what tyre size you choose to put on your bike. If you go too big it can greatly affect the stability of a motorcycle because the standard rim size is now too small for a bigger tyre. This will ‘pull’ the tyre into a profile that it’s not designed for, if you understand what I’m saying?

And things will get worse when the tyre becomes worn. An oversize tyre on the rear, when worn in the center, will certainly make the bike weave at high speeds when it becomes ‘square’, which makes the bike feel horrible and even a little intimidating to ride. An oversize front tyre will also make the bike harder to turn and therefore under steer in the process, which can be dangerous if you’re not expecting it to do so. So I’d recommend what the manufacturer recommends, very time.

A good site to visit is www.metzeler.com because they’ll tell you what you need to know for road, race and street applications.