Tire sizes - Upsizing, what will fit?

[Justin B.]

I finally got around to buying some high-dollar blasting grit since I realized Monte was never gonna bring me some of the cheap stuff...  After blasting and repainting the rear wheel I mounted the new 120/90-18 Macadam 50 tire.  

It looked a monster next to the stock size Metzler that came off and I was afraid I would have to machine a new inner top-hat spacer to keep it from rubbing the swingarm.  I slid it home and was overjoyed to see I had almost 1/4" of clearance!!    Again, good clean living must have prevailed as it rides as smooth as glass without balancing.

If I can point out any down-side is that both tires are just touching the ground when it's up on the centerstand.  I suppose a bit of welding will fix that, though...

[DgM]

On my 1983 R65 I've got 4.00x18 Avon on the rear wheel and 110/90 x18 Avon on the front wheel - they're about the same size - moved the front fender up a bit for clearance - and the ride quality as well as looks are much improved.  No clearance issues on swingarm. Okay, the bike needs to be pushed into a tight turn a bit and the center-stand doesn't raise bike up much off the tires.  Overall improvement.

[Justin B.]

I have a 90/90-18 on the front which provides great quickness.  I think the 120/90 would probably be approx. equiv. to a 4.50x18.  This was the size combination from my departed '95 R100RT and I had a spare set of tires to use up...

[nhmaf]

Justin will probably have even slightly more quick steering as the rear tire will be a bit more tall than the front, which will tend to push the head down/tail up and reduce trail, particularly with the 90/90 on the front.   I had a 90/90 on the front, but now prefer the 100/90 - it is a little bit slower turning in, but not enough to cause issues in the twisty parts for me, and is less nervous feeling on the interstate when jousting 18 wheelers..

[Justin B.]

Mike, I may try a 100/90 next time but I had this spare set left over and this was the stock size combination on the mono RT.  I've gotten used to the quicker handling with the 90/90 so that's not really an issue for me.  I was just just amazed that using a rear tire that much wider than stock still left me with that much driveshaft tube clearance.

[nhmaf]

I'm surprised too.   I *think* that I got the longer tophat spacer when I replaced the seals and bearings in my rear wheel.  I've got a 110/90 on the rear now but don't think I'd have much room if I tried a 120/90.  I do like the ability to get the wheel&tire off and out from under the fender without having to let the air out of it though - a major plus in my book.

[Justin B.]

I couldn't get the original off due to the bag racks so I have to give thanks to whoever it was that suggested removing the rear fender to ease tire removal/installation.  Much easier than the bag rack!