An odd tyre question

[CarlSV650]

Is there any reason why you can`t run a "front" tyre on the back of a bike?

I`ve just picked up a TZR250, the tyres are tiny F 100/80 rim17, R 120/80 rim17.

I`m thinking to get sticky rubber how about BT-090s, on the front 110/70 rim17 and on the back 120/70 rim17. So the tyre fitted to the back would be a fat front!

Anybody see any problems?

Racers use the 110/70 front so I know that`s ok.

Have a think.

[Carsick]

Not an expert here, and I can't say I know the tyre (or bike really) that you mentioned.
As far as I know the main reason for not using a front on the back is the tread patterns. Some tyres are designed specifically to go at one end with an appropriate one on the other, other tyres may not be designed this way.

[BURNER]

Tyres are sized for the rim size, so if you want to run a smaller rear tyre you'll need a narrower rim. Simple really :lol:

[CarlSV650]

The tyres are road legal race tyres, I used to run them on an NC35.

TZR250s were the best two stroke 250s until the RGV came along.

Hope that helps, and they`re 128kg. SO light!!

[CarlSV650]

Tyres are sized for the rim size, so if you want to run a smaller rear tyre you'll need a narrower rim. Simple really :lol:

They aren`t a smaller tyre.

[Carsick]

The tyres are road legal race tyres, I used to run them on an NC35.
TZR250s were the best two stroke 250s until the RGV came along.
Hope that helps, and they`re 128kg. SO light!!
That's how much I already knew, heh.

[embee]

....also no tyre expert, but most front and rear tyre construction is different, front ones take load under braking, rear ones driving forwards.

The guy on the Bridgestone stand at the NEC was explaining about using a BT011E front tyre on some bikes (oh alright, the Deauville :oops: ). It was originally developed for a bike (forget which, GSXR1000 or something) which had a certain, how shall we say, "character" to the steering at speed, so they made the "E" version with a rear-tyre type construction which altered the stiffness somehow to stop the wobbles.

Don't know whether it'll rule out using a front on the rear, but something to consider. The various tyre websites list tyre use F/R/or both.

Maybe a front tyre fitted backwards would work (from the construction point of view), but I don't know what an insurance assessor would make of it in the case of an "off" :?

[CarlSV650]

I`ve been told by a local tyre dealer that during the eighties it was quite common fitting fronts to the rear.

What he did say is NEVER fit them the other way round. Because the tread will then try to direct water toward the middle of the tyre contact causing serious aquaplaning!!

The forces involved in braking/accelerating have little effect, because while the tyre concerned is under load there`s downward force too.

Anyhow the problem`s been solved, apparently a TZR125R wheel fits straight in, allowing 140 rear tyres.

Cheers,

Carl.

[Flamin_Squirrel]

I also read on here that even for a given compound, they make the front slighty stickier to prevent the front braking away before the back. Something else to consider.

[embee]

....NEVER fit them the other way round. Because the tread will then try to direct water toward the middle of the tyre contact causing serious aquaplaning!!


Good point! :shock:

[SV650Racer]

PLUS most tyres have a fitment spec written on the tyre wall which will say either front fitment or have the direction of fitment. If you fit them the wrong way round etc and have an accident your insurance could be invalid and also can be deemed as an mot failiure if you get a pull by the plod...worth noteing as its done via the Dept of transport regs...

[SPeeeeDY]

i dont know much about tyres, but from what iv heard over the years is that the rear tyre is a very slightly harder compound to the front tyre of the same type (if you know what i mean) its is because of all of the torque pushed through the tyre, it would just shread a slightly softer front tyre. different 'molecular construction' or summat like that