Tire size for my 81 GS1100EX

[Jethro]

Don't have bike or manual in my garage this week, but need to order tires. Is the rear 130-70-17"? Can't remember the front. Also, someone posted a while ago a nifty guide that tells you what the largest tire you can put in our old GS's, but I couldn't decipher it. Anyone have an idea? What are the disadvantages of using a larger tire? Advantages? Thanks.

[Jeff Tate]

Rear is 130/90-17 and the front is 3.50-19. The H is rated to 130mph and the V is rated to 149mph.

[Anonymous]

Follow Slowpoke's advice 130/90-17 rear, 3.50-19 or 100/90-19 front. Do not go oversize, you'll ruin the handling. Tire sizes like 130/70 are made for wider rims and although you may squeeze it on the profile will be altered and may make your bike very unstable.
Axel

[Anonymous]

Oops, meant to say Jeff Tate, but I'm sure Slowpoke would agree.
Axel

[Jethro]

Ah, thanks Axel. That was my next question- if there was a conversion to metric. Brings up another question- last time I went to buy a tire, the dealer said he is never comfortable with putting a different model from ft to rear. I am sure he was just trying to get another 100 ponies from me, but is there any truth in this? He said that different compounds and tread patterns can cause tires to grip and slip differently from each other, that tires are designed to work as a pair. Any thoughts out there on this? Again, I'm sure he wanted a bigger sale, but it also makes some sense. I mean, no matter how tiny it is, tires do slip a little in a turn. Then again, I have run two different models of shoes for 3 years now and haven't noticed poor handleing.

[Anonymous]

tire size/matching

I'm no expert, but what I've read tells me that the tire manufacturers usually recommend matching front/rear because of the different compounds used. Some of the newer tires especially, either because of the radial construction/bias ply differences and also different tire compounds are more "sticky" to the pavement than others. High mileage tires are usually less "sticky" but last much longer. There are very sticky tires, but if you have an older bike, they can cause your frame geometry/suspension to undergo more load than originally engineered to handle(that's if you play ricky racer with them). Tires are extremely important in affecting handling characteristics and stopping abilitys, and I feel one should find out from manufacturer of your bike or tire company what is recommended and why. Usually reputable parts suppliers do get input from tire manufacturers, or if the service manager is older and been around, they will have the straight info as aposed to just a salesman. Seek out info where-ever and safe riding to you.

[Anonymous]

I think certain tires can be mixed with good results and others may not work worth a damn. Years ago I used a Metzeler Laser front with a Dunlop 591 rear and had no problems at all. I also tried a 140/80 Avon on the rear of my '82 GS1100E and it really messed up the handling. To me tires are the single most important thing on my bikes. They can radically change the the steering, the stability, suspension feel and traction, especially in rain. And when they start losing their profile the bike feels weird and I lose interest in riding it. Once I get a new set of tires on it I feel like I've got a whole new bike. So I don't take chances anymore, I always buy a high quality matched set.
Axel