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Post by jeronimo on Jan 28, 2008 1:04:49 GMT -5
I would like to know if it's safe to run tubeless tires on the cast wheels of my '78 SR 500? Years ago I went through all this with the snowflake mags on my 1980 R100. I ran tubed as well as tubeless without any problems with either. Tonight, for sale on e-bay, I saw a "dealer's only" manual from Yamaha covering the mounting of tubeless tires on the cast wheels from 1978. My wheels don't say "tubeless" on them anywhere.  Thanks and cheers. Jeron |
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Post by modrocker on Jan 28, 2008 7:57:22 GMT -5
I will gladly defer to the greater experience on this forum but I ran tubeless tires on the cast wheels on my 79 XS400. On the other hand, the owners manual for my SR states clearly that the aluminum wheels are not designed for tubeless tires. I just ordered tubes and tires for my bike...
I did want to add that the tires (for the SR) are "tubeless" but I am using tubes. On my old XS400, Iran tubeless tires without tubes (based on the recommendation of a trusted BMW mechanic/vintage racer)
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Post by G Man on Jan 28, 2008 8:15:36 GMT -5
Hi Jeron. I should assume pretty all tires available today would likely be tubeless tires. However, these are perfectly fine to use providing you DEFINATELY DO USE tubes in them. The rims bead seating area doesn't have as pronounced a bead lock as newer tubeless rims. Having the tube helps ensure the tire stays seated in the event your air pressure gets too low for one reason or the other and a possible un-seating of the tire from the rim could occur. YMMV of course...
G Man
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Post by miker on Jan 28, 2008 9:35:41 GMT -5
In case anyone missed it, the 78-79 (disc rear) SR's have non-tubeless rated cast rims and the 80-81s (drum rear) *are* tubeless rated. This parallels the XS650 cast wheels, which actually came both ways 78-79 but were all tubeless 80-81.
Generally if you're running a tube in a tubeless tire they say you should derate it one "speed rating" letter because of heat that can build up between the tire and tube.
miker
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Post by jeronimo on Jan 28, 2008 14:50:53 GMT -5
Thanks to all who responded. I have new tires w/ new tubes waiting to go on my project bike and was wondering if I could knock off a little extra weight. I will run tubes, thanks to the info y'all provided. Thanks again, Jeron.
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Post by caferacercarl on Jan 30, 2008 2:08:02 GMT -5
G Man is dead right about the flange where the tyre mounts and miker on the speed rating...take notice everyone about SR wheels needing tubes as your local shop probably couldn't tell you and it could "all end in tears" I remember guys hitting potholes and losing pressure. may your lid never skid...
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Post by jeronimo on Feb 1, 2008 4:30:34 GMT -5
So, I'm at the bike shop today gettin' my rear tire & tube mounted when the proprietor asks me "Why ya puttin' a tube on this wheel?"...............I explained it to him.
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Post by caferacercarl on Feb 14, 2008 3:02:47 GMT -5
Your one up on the shop, good on ya buddy, keep asking questions and have no problems as a result, clever man.
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Post by stevec5000 on Mar 29, 2008 23:40:30 GMT -5
Some people will claim you need to use tubes in older cast wheels because they are somehow different but that's not true. They are exactly the same as far as the wheel edge where the tire seats. Older cast wheels were not rated for tubeless tires because they didn't have tubeless tires generally in use back then and they didn't predict the future. I'm using tubeless tires without tubes on my '78 but I had to mount valve stems in the holes and clean up the edges of the wheel a bit where it's been scratched by tire irons over the years so the tire would seal against the edge and it works fine.
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Post by manxman on Mar 30, 2008 1:00:34 GMT -5
Some people will claim you need to use tubes in older cast wheels because they are somehow different but that's not true. They are exactly the same as far as the wheel edge where the tire seats. Older cast wheels were not rated for tubeless tires because they didn't have tubeless tires generally in use back then and they didn't predict the future. I'm using tubeless tires without tubes on my '78 but I had to mount valve stems in the holes and clean up the edges of the wheel a bit where it's been scratched by tire irons over the years so the tire would seal against the edge and it works fine. Dogpile anyone? |
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Post by G Man on Mar 30, 2008 7:54:07 GMT -5
Some people will claim you need to use tubes in older cast wheels because they are somehow different but that's not true. They are exactly the same as far as the wheel edge where the tire seats. Older cast wheels were not rated for tubeless tires because they didn't have tubeless tires generally in use back then and they didn't predict the future. I'm using tubeless tires without tubes on my '78 but I had to mount valve stems in the holes and clean up the edges of the wheel a bit where it's been scratched by tire irons over the years so the tire would seal against the edge and it works fine. You make mention of the wheel edge where the tire seats. It sounds like you've determined that a clean curled up edge and holding air is the criteria for whether a person should run tubes or not. Actually, keeping the tire "locked" on the bead area should you lose air pressure while riding due to tire damage (nail etc...) or have a sudden very harsh impact is what the concern should be. If you do not ever experience any adverse conditions (impact or rapid air loss), you "may" not have an issue the way you are set up. It's not a chance I recommend taking though. If you do have an issue, dire consequences could be the result. Modern rims that are designed to be run tubeless have a very pronounced lip that the bead of the tire needs to be forced over before coming to rest against the curled up edge of the rim that you have prepped and cleaned. Here's a small pic and make note of the raised lip about 1/2 to 3/4 of an inch inside of the outer edge:  The rims on the early years of SR do not have the lip. The tube is in there to help prevent the rapid and complete loss of air and the immediate derailing of the tire should you have some kind of issue. Skating down the road on the bare rim edge itself is something that you will not experience for very long prior to crashing the bike... Disclaimer: Take what I have said here with a grain of salt... YMMV and all of that... Always use your best judgment and take all precautions to keep yourself safe. G Man |
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Post by stevec5000 on Mar 30, 2008 9:30:34 GMT -5
We aren't talking about "modern" rims but ones on 30 year old bikes! None of my Yamaha alloy wheels have a ridge inside the wheel to hold the tire. Besides the '78 SR500 I have a '79 XS750 that had tubes and I also have an '80 XS850, '80 XS1100 and '81 750 Seca that had tubeless tires. Once when I was putting on some new tires and moving some others around I set all the wheels from them side by side to compare and there was no difference.
The newer wheels have a deeper center area that makes the tire easier to change but the edges are the same.
I just changed a tire on my buddy's Suzuki 1200 Bandit and it does have ridges to hold the tire in place but it's got much wider tires that are almost like car tires so I assume the ridges are a newer improvement that was added to the wheels in later years when the tires got wider and the bikes got much faster. The narrow tires used on our older bikes don't need a ridge since they are so stiff they can't move anyway. Like I said some people will claim that Yamaha wheels are somehow different for tubes vs. tubeless but they are really not.
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Post by G Man on Mar 30, 2008 11:57:48 GMT -5
... so I assume the ridges are a newer improvement... Like I said some people will claim that Yamaha wheels are somehow different for tubes vs. tubeless but they are really not. Unless your rim is stamped tubeless, you must use a tube. Even with a tubeless tire. Here is a link to a page on tire installation from the Yamaha SR500 Service manual. See the warning on the top left of the page: www.slash5.net/sr500/b0000ddd.gifIf it is only your opinion (which you are fully entitled to) that one can use a tubeless tire without the addition of a tube on a Yamaha SR500 cast wheel that does not have the word tubeless stamped on it , then just add such notation to your post. If you can post printed fact that says otherwise, then please do so also. I would be very interested to read it. Otherwise, I do not want people to be ill informed on this issue. G Man |
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Post by davewfc603 on Mar 30, 2008 23:11:05 GMT -5
I just put tires on my 79 BT45's with tubes, as written above it drops the speed rating down 1 level. I think all the tires I looked at to buy exceeded the speed of a SR500. That helped to answer my tube/tubless question. Dave
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Post by joneill4 on Apr 2, 2008 13:58:31 GMT -5
Drop the speed rating down one?!?! No way! I paid all that money for tires that are rated for 130MPH, and you guys are telling me that I can only go like 120?!?!? That ain't right.
Yeah I know...a day late ; )
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Thanks and cheers. Jeron
