fattest in the rear?

[Anonymous]

Ok, time for the next mod. I just swapped out the swing arm on my 77 gs550 for one from a 78 gs 750 (to get disk brakes back there), anyway, it came with a stock tire and that looks skimpy.So, after all this rambling...whats the largest tire that can be squeezed back there?

Thanks,
Mike

 

[Anonymous]

i had a 4.50 on my 78 gs750 that is the widest that would fit

 

[Anonymous]

Rick,

Thanks, 4.5 is the width right?...what was the aspect ratio for that tire..if you remember?

 

[Anonymous]

I have a 4.60/80/18 on my '79 gs750. It was on there when i bought the bike. Anyone know what this converts to mm? ~180mm?

 

[Anonymous]

around 120mm

 

[Anonymous]

I recently found out from Bridgestone tires, that the absolute largest size that can safely be used oun our '78 GS750E is 130/80 (rear) and 100/90 (front). He recommended a 120/90 for the rear though, suspecting that the tire might rub on the swingarm. I just ordered their BRIDGESTONE S11 120/90H18 rear, and 100/90H/19 front, but have not installed them yet.

 

[Don Lobacz]

I run a 140 on a Lester rim on my GS1000, and it just fits. I was under the impression that the 750 and 1000 swingarms were the same width with the same chain clearance.

 

[Anonymous]

I am running a Barracuda 130/90 on my 78' GS750 with no problems. Not the most expensive tires but a good value for the money. Greg

 

[Anonymous]

I'd say it depends on the tire manufacturer as well. I've got a Bridgestone 130/90 on the rear of my '83 750ED, and it rubs the caliper arm slightly. It's a new tire that was on the bike when I bought it (5 weeks ago), and it seems to have worn the millimeter or two off of the side that was rubbing. I've heard that this is an acceptable size for this bike, but I'll be going back to a 120mm width when I change it out. It's not just about the widest tire that'll fit while your bike's standing there - bear in mind that your wheel will flex under hard cornering, the air in the tire will expand when it heats up, and your bearings have enough play to allow the axle to travel a bit. The worst time to find out that your tire's too wide is when it grabs onto your caliper arm at speed in a curve...

 

[Anonymous]

sounds like the concensus is around 120mm or 130mm, thanks for the starting point guys!

 

[Billy Ricks]

Don't go more than one size over stock. You pinch the sidewalls too much when you do. It leads to too much flex as has already been pointed out and less contact patch in the upright position.

Q!, you can bend the torque arm a bit to clear the tire. I'm running a 160 on a 4.5" Gixxer rim and had to bend mine for clearance.

 

[Anonymous]

Hey Billy - how much did you bend it, and did you have to tweak the caliper to make it match up?

 

[Billy Ricks]

Hey Billy - how much did you bend it, and did you have to tweak the caliper to make it match up?

Quite a bit, it pretty much follows the line of the swingarm. Didn't effect the way it connected to the caliper at all. The caliper hanger pivots so even if you end up rotating the caliper towards the bike's front it doesn't matter. My torque arm is now mounted on the bottom of the swingarm for the Gixxer caliper.