Wheel Rim valve holes

[randy]

Rear rim has 3 valve holes! What's up with this? Are there plugs for the unused ones so I can use a tubeless tire?

[Jerry]

Randy:

Two of the holes are for "rim locks" used on tube-type rims. Do not run tubeless tires on these rims! The rim design for a tubeless is different. The rim you have is designed for a tube-type tire only. If you do not have the 2 locks (about 6 - 8 inches long with a threaded stud that goes through the holes in the rim) check with others on this list to see who might have a pair they will part with.

If your rim is a 16 incher (rear) or the 19 inch front, you can swap in the later XS ('80 - '81?) or XJ ('82 in the US, through '84 in Canada) front and back rims to get tubless capability. If you examine the rim there will be, cast into a spoke, either the word "Tube" or "Tubeless" to identify which rims are designed for tubeless tires.

[randy]

Jerry, Thanks for the quick reply, but the Yamaha factory part #'s for the tube and tubless rims are the same so the only difference is the holes. Right?

[Snow]

If I remeber correctly, Yamaha tested the rims before marking them either tubed or tubless and if a rim was found to not be perfectly leak-free, then they marked them tubed and added the other two holes?

[randy]

Thanks. The rims were cast with the three holes. We have the same model, 1979F Standard. Do you have the same issue with the rims? I find it hard to believe that Yamaha would equip some units with tube and others with tubless, unless tubeless was an option??

[Ken Talbot]

... you mean I can't put in a special tube with three stems so when I roll up to the airhose I don't always end up with the stem up where I can't get at it?

[randy]

We're not in Kansas any more..... Seriously, folks, did 79F Standards come tube or tubless?

[Snow]

My 79F had tubed rims - I got a pair of tubeless off ebay on the cheap

[Jerry]

This is from memory, so take it with a grain of salt.

The conversion from tube to tubeless was done during the '79 - '80 model year. Yamaha used up the tube rims it had and began installing tubeless in the middle of the production run. So yes, you could have either a tube or tubless rim depending on your bike's place in production.

I think all 17 inch rims used in the early XS models are all tube-type.

Tubeless rims are shaped differently from tube-type rims. Tubeless tires have a different bead angle; I recall it is somewhere in the neighborhood of 15 degrees different. This is the main reason why you can't just plug the holes in the tubeless rim, mount a tubeless tire, and go; the tubeless tire to tube rim doesn't give you a reliable seal, particularly when used on a big, heavy motorcycle. On a car it is less of a problem.

If I can find the site that showed the cross section of a tube and tubless rim I'll post the URL here.

[randy]

Thank you Jerry, for your most lucid response.

[Jerry]

I can't find the URL that shows the difference in bead design on both rims and tires, but I have found many references to it. For a really technical discussion of motorcycle tires, link to this .pdf:

http://downwardspiral.net/motorcycle/mcintroe.pdf

[strom]

OK, I got a 78E
There is no marking on the rims, whether they are tubeless or tube type.
However, the rear rim has rim locks, the front one does not.
Gotta change the tires....
Option 1: Bridgestone BT45 (I think) with tubes
Option 2: Avon something... gotta get the prices and stuff. Any experiences with these?
Option 3: Kill the dunlop dealer for not getting me K491s...

LP

[stevec5000]

You can use any tire you want that fits, it's up to you. There is no difference between Yamaha's tube and tubeless rims unless you have the lock holes. It's an urban myth or old wive's tale that the rims are different. Lot's of people like to spread silly stories like that, don't know why. Too much time on their hands maybe.
They started marking them all tubeless after '79 but it's the same rim. I once compared the rims from my Yamahas for '77, '78, '79, '80, and '81 and the bead areas are all exactly the same. There is a difference in the center of the rim for '77 and '78 compared to the newer ones, the center isn't as deep and rounded like a tube on older ones while the later ones are deeper with square sides making it a lot easier to change a tire. You can put a tubeless tire on any of the rims with no problem but if you have one of the older wheels with the rounded area in the center you might want to replace it for easier tire changing.

[Winterhawk]

Tubless will work just fine on a 1978 with tubless and rim locks Plug the other 2 holes with a bolt, washer. rubber washer/o-ring and locknut. I've known people who have ridden for years with this setup.

[2fast]

Uh, Ok, I dont get it. Whats the big deal with installing a tube on a rim that is designed for a tube and tire? Why second guess the safety or functionality of replacing it with a tubless type instead of just running a tube and tire? I would not fool around with nuts and bolts as fillers and just hope you get as lucky as someone else who may have tried it! You have two wheels, and two wheels only, which one would you say in unnecessary? Sorry, I just don't get the debate....stick in a tube and go ride!