Tires for '78 GS550

[Anonymous]

Hello,
I just got this bike in the beginning of the riding season and its time for some new tires. I want to make sure I get the right ones, so I figured i'd ask here before making any decisions. Again, the bike is a 1978 GS550.

I have found these tires, first off will they fit? The rear is a bit wider than the one that I have on it now, I have a 110 and this will be a 120.

Metzeler Lasertec 120/90V18 Rear Tire

Now for the front, are these two tires essentially the same other than the speed rating?

Metzeler Lasertec 3.25H-19 Front Tire
or
Metzeler Lasertec 110/90V-19 Front Tire

Are there any other tires that any of you would recommend?

Thanks,

Vance

[Anonymous]

I have tried searching everywhere, different message boards and everything, and I cant really seem to find an answer. I hope to buy a new set of tires by the end of the week, does anyone know if the 120 rear tire will be ok?

Thanks,

Vance

[IanFrancisco]

I had to go with 90/90-18 front and 110/90-18 rear on my GS450S which is not that much smaller than your 550. I went with Avon AM21/AM20 (Roadrunners). I might have been able to squeeze 120/90-18 on the rear but I would have had to not run a front fender to get 100/90-18 on the front. I originally wanted Dunlop GT501. The GT501 in 120/90-18 that I bought first was close to 120mm (4.72in.) wide. The AM20 110/90-18 I ended up with is larger than 110mm (4.33in.) closer to 4.5in. wide. It went in easy, clears the swing arm by about 1/4in. at the widest points. Just remember that the tires may not be the size they say they are and take a tape measure with you. Measure what you have already and measure what you're looking to buy if you can. I was dealing with an online store and had to pay 15% restocking fees TWICE 'cause I ordered too large the first time(s). I did my tires separately (different days, months actually).

Here's a link to some info for your bike. Can't vouch for its accuracy though:

http://www.azmotorsports.com/Specs/Suzuki/Suzuki_Specifications/suzuki_specifications_137.html

Says the OE tires sizes are 3.25-19 front and 3.75-18 rear. I had a 3.25-18 Continental ribbed front that was rotten and cracked. The 100/90-18 GT501 I bought was WAY wider than 3.25in. closer to 4in, which is what it should be. In other words don't believe the tire size conversion charts. Your Mileage May Vary. The 90/90-18 Avon AM21 was close to the same size as the 3.25-18 it replaced even though 90mm is 3.5in. It may have been 1/4in. larger, it was two mos. ago now and you know the memory is the second thing to go... ;-)

Here's a link to a US-MEtric conversion page. Very handy.

http://www.usa.ru/calc.html

[jimcor]

I checked my Clymer 550 manual and tire sizes are not listed. From memory, the older 550s used a 3.25X19 Front and a 3.50X18 Rear, or a 100/90X19 Front, and a 110/90X18 Rear. I would not try to go bigger or smaller than what was originally on the bike. Call Dennis Kirk tech support. 1-320-358-4793. They can tell you what you need, sell it to you if you wish, and send you a free catalogue. Get the free catalogue, it's an inch thick full of part and accessories and chock full of information.