Widest rear tire size (not what you think)

[soulmachine]

As I was cleaning up the rear brake drum from grease that turned to liquid (what should be used for those splines anyhow?) I noticed how tight it was, not only to get the wheel fed in and out of the swingarm/brake, but how close the tire is to the arm itself while mounted.

This brings a question to mind.

What is the widest we can go on a dual shock R65?

I ask because I have been sitting on a set of tires that I really want to use up. The rear is a 120. But I have my doubts now that I've had a closer look.

[Bob_Roller]

It depends on the tire, I've been using Metzeler Me33 Me99, now the Lazertec series tires, since '86 .

A 120 width is the widest tire that will fit and I have the same issues as you described, a pain to get on and off .

When these wear out, I'm going back to a 4.00 width rear tire .

I think everyone has their one preference for spline lube, I mix a Moly paste with thick wheel bearing grease for the final drive splines .

I don't know if in the long run it really matters what you use, as long as you clean and reapply the lubricant before any rust shows up .

If the liquid you are cleaning up in the rear brake area, smells like gear lube, the O-rings on the rear brake cam shaft may be starting seep / leak, not an uncommon problem with these bikes .

[soulmachine]

If the liquid you are cleaning up in the rear brake area, smells like gear lube, the O-rings on the rear brake cam shaft may be starting seep / leak, not an uncommon problem with these bikes .

I will take the wheel back off and pay closer attention at that area. Just casually looking at everything, it just looked like the grease was thinning out. Nothing looked wet, perse...

[Barry]

There is no common dimension fora specific size of tire.  A 4.00  tire for example is always significantly wider that 4"  Metric tires are closer to the nominal size but still not exactly 120mm wide.

What I suggest you do is accurately measure the tire you have installed and also the clearance this tire has to the swinging arm. Then you will have an answer.  When I did this I concluded that 120mm is the maximum I could safely go to and still have at least 1-2 mm clearance.  I'm currently running a 4.00 M45 which is 118mm and I have 3 mm clearance.

[georgesgiralt]

You can move the wheel slightly from the brake by using a top hat spaced larger than the standard one. It shows in the fiche. But you won't gain too much. Measure your actual before ordering.. don't ask me why I know this...
As per lubing the splines, go to the nearest "industrial store" (where mechanics buy ball bearings, lubes, hydraulic components and the like) and ask for an extreme pressure static lubricant. They will offer you something in the line of the Honda Moly or Molykote BR2 or the house brand. These lubricants are very solid and stay put. This is perfect for our use. Of course do not use the whole tube on one application ;-)
P.S. : Always wear gloves when using such lubricants. They are aggressive to the skin and can cause allergies. They contain nasty chemicals. I've found Nitrile gloves to be perfect for the job.

[Justin B.]

I have mounted a Michelin Macadam 50 120/90 on an '82 LS and did not rub...

[thrang]

I've got a 120 Conti Go on my LS and its not rubbing.

[Barry]

Some oddball things about rear tire fitment:

In the case of the BT45 the 120 tire is actually narrower than the 4.00.  

The 78-80 swinging arm is not the same part as the 81-84 which is longer and may also accommodate a slightly wider tire.

[soulmachine]

Either way, the tire I have doesn't have a chance of going on, easily anyhow. Rough caliper measurement comes up as being 127. So, these tires I have aren't going to work. Thanks for the information.

[wilcom]

the tire I have doesn't have a chance of going on

You can always air it up "after" you get it on the bike. If you don't have 127 in the swing arm, then that"s another problem............

[Bob_Roller]

I deflate the tire before trying to remove the tire / wheel from the bike .
I just remove the valve core .

Also, the 120 width Metzelers don't contact the swing arm, but there is at best 3 mm clearance between the two .

[soulmachine]

I guess I should have mention that what I have are dual sport tires.

So, these tires will not fit.

[jonathanrowley]

I've got TKC80s on mine and they are 3.5 at the front and 4.0 at the Rear I believe.

Still leave a good gap and work fine on and off road.

[soulmachine]

I have an old set of Pirelli MT50's that I've been hanging onto like grim death...and I don't know why. I really don't have anything that they will fit onto. I bought them for an old 900 Sportster I had. That was long ago. As it is, the rear is simply too wide. Far too wide.

I'll spring for a set of Heindenau tires, and finally let go of these old MT50's.

[Barry]

How old is old ?

The rubber will have hardened up and will provide less grip.  I think the guidance is never mount a tire more than 6 years old and scrap any tire in use when it's 10 years old.  Tires are not necessarily catastrophically unsafe when they get old but there is no question that grip is reduced.