Triumphrat

jellero · 06-04-2005

aside from size... some bikes use the same sizes, like my harley. it used to be customary to rotate the tires every couple thousand miles and both were the same. i asked a few tire people and they didn't know. one told me that the rear tires were a heavier duty, so if that was true, why not just use rear tires front and rear? i'm skeptical... anyone know? j

preachp · 06-05-2005

Hi Jellero,
The tread patterns are different. The front tire must maintain traction during hard braking, the rear during acceleration. The rear tire is exposed to the twisting forces applied to it during acceleration. the rear has to have a larger cross section to maintain traction during that time. The front has a much rounder profile and a narrower radius to facilitate direction changes. The compunds are different with the front being a softer compound. The reason being the rear would be gone in short order with today's high powered engines if it were as soft as the front. The front is also smaller to reduce the reciprocating mass and the rotational forces on the front. This helps with suspension and also handling, and braking by reducing unsprung weight, the gyroscope effect, and the amount of rotating mass the front brake is fighting.

Hope this helps

Preachp

welshrob · 06-05-2005

Quote: why not just use rear tires front and rear?

Because then they wouldn`t be rear tires, they`d just be tires. :-D

Eclipse_Blue · 06-10-2005

Er? Could it be that the rear is bigger than the front and that it is on the rear of a bike while the front is on the front of the bike? Dunno if that helps

mattbin · 06-10-2005

The tyres also have different carcases to resist acceleration (rear) and deceleration (front) forces which is why they also have direction indicators. Its not such an issue with a small bike, I had a 500 single that had the tyre put on the 'wrong' way round (direction wise) called Avon and they said it would 'probably' be OK, but definitely a no-no on a big bike with much heavier forces being transmitted.

HTH
Matt

jellero · 06-10-2005

matt, i just got that info today that the tires are made "backwards" in the core layup for those reasons. the treads are identical with my tires as are the sizes on my harley. thanks. i sure got a lot of stories about this over the years... j