Should I mount Metzeler Cruisetec tires or return them?

Hey everybody. I'm kinda new here so forgive me if this question is asked all the time. Got my first bike a couple months ago. It's an 81 650 Maxim. I did a bunch of basic, non technical work to it and now its running pretty good. I ordered Metzeler Cruisetec tires with all the same numbers as the Dunlop D401 tires that were on the bike when I got it. The rear tire looks like its about 1/2 inch wider than the Dunlop. I'm worried that it will rub on the drive shaft housing, since the Dunlop had roughly 15/64 clearance. The Metzeler website said it should fit and 81 Maxim, the guy I talked to from Revzilla said they would fit, but I thought I would ask the good people here what's up. Put 'em on or follow my gut and return them?
Side question:
The rims are dirty. Can I pressure wash the wheels while they're off the bike without taking the bearings, gear, and brake drum out, or is that a bad move?
Side question 2:
After I took off the rear wheel I found a stainless steel ring on the floor. It's a split ring that's about 39.4mm ID and 44mm OD. Does this sound like a part of the wheel, or something that was just floating around my garage? I don't see it in the service manual I downloaded.

 

Hi there!

The tire will most likely become noticeably narrower once it is fitted on the rim.

If you plan to pressure wash the wheels off the bike, you must first seal all bearings so that no water will ingress.

Cannot answer about the ring.

 

The tire fits on the bike, but now there is some kind of metal rubbing noise when I spin the back wheel. I also can't tighten the axle nut anywhere close to what the manual says, the wheel stops spinning at roughly 10-15 lb-ft. I wonder if that little ring is some kind of spacer. I just can't see where it fits in the wheel, or find it in the manual. I don't see what else I might have missed. It looks like everything is there that came out as far as I can tell.

 

Could you post a photo of the ring thing?

 

These diagrams should hopefully help you https://www.partzilla.com/catalog/yamaha/motorcycle/1981/xj650-xj650h/rear-wheel and https://www.partzilla.com/catalog/yamaha/motorcycle/1981/xj650-xj650h/drive-shaft

If the wheel is binding, and did not before and you have not changed the wheel bearings, my first guess would be that you have omitted the spacer #43 in the final drive diagram. Or the wheel has not bottomed/seated properly on the splines and is binding, causing unwanted forces on the final drive gears. .

 

It kinda looks like it fits between the hub gear and the gear in the final drive, and it makes the rubbing sound stop but doesn't solve the torque issue so I'm hesitant to try it.

 

That spacer looks like it's in place to me, and the noise sounds more like aluminum than steel. One thing I noticed when I took the wheel off was that the axle nut was super loose, like barely finger tight once I took out the cotter pin.

 

Perhaps the ring was placed there in an attempt to get rid of the rubbing? It looks like something that could live in a seal, to give it extra strength, but I do not think it belongs were you placed it.

However, to me it looks like the spacer is missing, although I could be mistaken. It should protrude a little from the drive unit. Here is a picture with it in place.

 

You're totally right, I thought I was looking at it but now that you point it out to me, I see that it's missing. Thank you. I don't what know what would happen if I ran the bike without that but you probably just saved my old Maxim.

 

Having to replace a damaged final drive would be the least of your worries - much worse if it locked up solid around a high speed corner, as there is nothing you could have done to get the wheel rolling again. But you would likely have been warned by a wobbling rear wheel and horrible noises before it got that far