what is the fattest tire size?

BohicaBob wrote:

It is a wise practice to never mount a tire larger than the rim was designed to support. This is very important safety and handling issue.

And, of course, you may have another issue: the larger tire interfering with your swingarm. On my '78 KZ1000, I run a 130 X 18" Bridgestone SE11 rear tire on a DID 3.00 X 18" rim and there is very little clearance between this tire and the engine-side of the stock swingarm, so much so that if I don't have the rear wheel properly centered, the tire will rub against the swingarm....

Dittos.

I've noted the same issues, even running a 130 x 16" rear (with rim locks) on a stock KZ swingarm. Leave the tire pressure a little low for traction, wank it up *real* good for a smokin' hole-shot and find out a little later that a fair contribution to the fog was coming from the sidewalls. :blink:

With wider tires, there's also an issue of a smaller tread profile meeting the pavement at greater lean angles as a result of the increased radius of the tire section. Seems counter-intuitive, but that's geometry for you. Not as much of a problem with a soft-compound tire, but a wider, harder meat on the a$$ end will break loose sooner in a hard turn than a narrower tire.

I run a Metzler 130/80x18 on a 3.5" wide rim on my KZ. No problems with clearance. I know of a few who have mounted 140 tire but sometimes they rub and sometimes they don't. Lot depends on the tire profile. Check the tread width measurement if you can find one. You will be surprised the difference between tires. Only takes a 1/8"-1/4" difference to make a headache. I've seen the chain hit first and other times the swingarm was the limiting factore. Guys have even put the tire on and after starting bike and putting in gear, hold a file to the outer edge of tire hitting chain/swingarm and file off however much rubber to make clearance. I would rather but next smaller tire on myself, but I've seen this done. Each their own! Also, been told to keep relative siaze difference front/rear same when changing tires...bigger rear tire needs a bigger front tire, but I've NEVER ran into a problem after mounting the 130 tire on the rear with stock size on front. I've even scrapped side of exhaust in leaning in corners without problems with bigger tire on rear, so I wouldn't worry about it.