Rear or front..whats the differences??

[chuck hahn]

Never knew this but it always bugged me why tires are either rear or front. Cant a front tire be run on the rear if its the same size?? such as the GSs that use a 120/90 X 17 rear tire. Not many "rear" tires show up in what i have looked at but many 120/90 X 17 fronts are listed. Which seems rather odd as most front tires are a bigger rim than 17 inches. Anyway, why cant a "front" tire be ran on the back...or can they???

[Steve]

1. Rear tires usually have a heavier weight rating.
2. You used to be able to tell direction by the tread pattern, but some manufacturers are going against the grain with patterns that seem to be backward.
3. Not sure if it's still true, but tires used to be made by rolling many layers of fabric and rubber. Think of it like a roll of tape. If you run your fingers in one direction over the end of the tape, it just slides off, but if you go the other direction, you might catch it and start peeling it off.

Now think of what forces are acting on the tires. With very few exeptions, the front tire only steers and brakes. On virtually all bikes, the rear helps with steering and provides all the drive force and very little braking. The front and rear have opposite demands on the tire, so if you do use a tire at the "other" end, you should turn it around. The tires that can be mounted at either end (per manufacturer's recommendation) will have direction arrows with both labels and they are going opposite directions.

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[hillsy]

http://www.avon-tyres.co.uk/motorcycle/faqs

Can I fit a front tyre on the rear and a rear on the front?

Avon would not normally recommend this fitment. If you do this however, due to the way tyres are manufactured, you should reverse the tyre’s direction of rotation if you fit a front tyre on the rear or a rear tyre on the front of your bike. During tyre manufacture, a length of tread rubber is wrapped around the carcass and joined together with an angled bevel type joint. This joint is orientated so that as the tyre rotates, this joint stays shut. As the rear tyre provides drive and the front tyre provides braking, the joint is made one way for the rear tyre and the opposite way for the front. Fitting incorrect tyres could cause potential MOT/insurance issues and may affect the bikes handling capabilities.

[Sandy]

In the old TT100 days a rear tire was commonly fitted to the front. I wouldn't put a front on the rear, just doesn't seem right for some reason. If putting a rear on the front the direction arrows should be reversed. The arrows are intended for which direction the torque is applied to the tire. Braking force on the front is opposite the power force on the rear. I've seen tires designed for both front and rear and the arrows for either end point in different directions. They make real decent front tires these days so why would you want to put a rear on the front anyway?

[Steve]

They make real decent front tires these days so why would you want to put a rear on the front anyway?

It's actually quite common on larger bikes with sidecars or trike conversions.

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[hillsy]

I had a rear BT45 150/80-16 on the front of my Intruder. On such a bike heavy bike it made sense from a wear perspective and the handling was fine within the limits of the bike.

[Sandy]

It's actually quite common on larger bikes with sidecars or trike conversions.

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I guess I'm wasn't familiar with those applications. Learn something new every day.

[bwringer]

Several sizes in the Avon AM26 RoadRider are made for front or rear use -- the direction arrow points one way for use on the front, the other way for use on the rear.

Generally, rear tires are a bit sturdier and have more tread rubber. They won't hurt anything when used on the front, but they also might have a slightly less than ideal feel (heavier steering, a bit less responsive) than a tire designed and optimized for use on the front. Overall it's not usually a huge concern.

When tires designed for front use are used on the rear, you can expect more rapid wear, and they might not have the weight rating you'd expect. But if you're trapped in outer Mongolia and that's the only tire the guy on the camel happens to have strapped to the rear hump, it's no time to get picky... anywhere else, I'd definitely try not to put a front tire on the rear.

[chuck hahn]

Price range I can afford is why Steve. Many of the 17 inch REAR dont show a 120/90 size. So if I get a front thats 120/90X17 run it with the arrow facing opposite..got it.