Tire pressure

I ran tubeless in my Lesters before the wreck. The rear was ruined but the front was in good shape but it lost air slowly. I put a tube in it but switched to wire wheels soon after. No noticeable cracks in the Lester but I got rid of it anyway. Big mistake.
Steve

This is the way it used to be when folks were imo well-advised to always use a tube when fitting any tire onto a wheel not specifically designed to be run tubeless.



Those who ignored the advice and ran tubeless tires without tubes on wheels designed for tubes (i.e., without the ridges), risked blow-outs -- instant full deflation -- instead of slow-outs. Not to mention the risk of hitting a bump while heeled over in a curve with too low air pressure whereby the non-tube and non-ridge conspire to allow the tire to slip off the rim. Not a joyful situation.

But if it's guaranteed that the air pressure will always be sufficient and that the tire will never lose air for any reason under any circumstances and that the rider will never heel it over too far and never hit a bump while cornering, it's probably then okay to run a tubeless tire on any wheel that can hold air without a tube.

Your butt. Your choice.

Good Fortune!

The top rim is a B**ch to change tires on. I've done em. :dry:
Steve

Patton wrote: This is the way it used to be when folks were well-advised to always use a tube when fitting any tire onto a wheel not specifically designed to be run tubeless.

Those who ignored the advice and ran tubeless tires without tubes on wheels designed for tubes (i.e., without the ridges), risked blow-outs -- instant full deflation -- instead of slow-outs. Not to mention the risk of hitting a bump while heeled over in a curve with too low air pressure whereby the non-tube and non-ridge conspire to allow the tire to slip off the rim. Not a joyful situation.

But if it's guaranteed that the air pressure will always be sufficient and that the tire will never lose air for any reason under any circumstances and that the rider will never heel it over too far and never hit a bump while cornering, it's probably then okay to run a tubeless tire on any wheel that can hold air without a tube.

Your butte. Your choice.

Good Fortune!

Patton,

Sorry man but this information is not entirely correct.

The front wheel on my KZ750 was imprinted "tubeless", however there are NO tubeless ridges. I have a Suzuki GS wheel that's same.

These extra ridges are a safety feature, they are not a required feature for use with tubeless tires.

There is no risk of blowouts running tubeless on wheels w/o the ridges unless someone lets the air pressure fall to a very low value, in which case you are at serious risk even if tubes are present.

Okay,I think I've gotten to the bottom of all this.No,I aint gonna die.It appears my front rim is a tube type and my rear rim is tubeless.Here's what I found.I got a Clymer manual today in reading the section on wheels,this manual covers multi year and models,it says on some later models tubeless rims were used.It says to check for a marking on the rim to designate "tubeless".I looked at the rims and the front rim is marked "J 19XM1 2.15 DOT" this rim has a valve stem that is for a tube,straight,threaded stem with the locknut.The rear rim has a tubeless valve stem and the marking on the rim says "T16X3.00TL DOT".I am assuming the TL is for tubeless.Anybody knows any reason my assumption is wrong,I'm sure you'll reply.Thanks for all the replies and opinions so far,its great to see so many are active here and willing to help out.Hope I can be as helpful after I get re-acclimated with the KZ,I did have a couple back in the '70's but its been many years and many bikes since then.This is a great site for info.

Nessism wrote:

Patton wrote: This is the way it used to be when folks were well-advised to always use a tube when fitting any tire onto a wheel not specifically designed to be run tubeless.

Those who ignored the advice and ran tubeless tires without tubes on wheels designed for tubes (i.e., without the ridges), risked blow-outs -- instant full deflation -- instead of slow-outs. Not to mention the risk of hitting a bump while heeled over in a curve with too low air pressure whereby the non-tube and non-ridge conspire to allow the tire to slip off the rim. Not a joyful situation.

But if it's guaranteed that the air pressure will always be sufficient and that the tire will never lose air for any reason under any circumstances and that the rider will never heel it over too far and never hit a bump while cornering, it's probably then okay to run a tubeless tire on any wheel that can hold air without a tube.

Your butte. Your choice.

Good Fortune!

Patton,

Sorry man but this information is not entirely correct.

The front wheel on my KZ750 was imprinted "tubeless", however there are NO tubeless ridges. I have a Suzuki GS wheel that's same.

These extra ridges are a safety feature, they are not a required feature for use with tubeless tires.

There is no risk of blowouts running tubeless on wheels w/o the ridges unless someone lets the air pressure fall to a very low value, in which case you are at serious risk even if tubes are present.

Thanks, Ed!

The front wheel on my KZ750 was imprinted "tubeless", however there are NO tubeless ridges. I have a Suzuki GS wheel that's same. ---- Am thinking that the earlier style tubeless wheel design with raised ridge evolved into a tubeless wheel design without a raised ridge.

Where the FSM specifies tubeless tires and is consistent with an oem wheel marked tubeless, running tubeless seems perfectly okay.

However, where the FSM specifies tubed tires for the oem wheel, tubes should imo always be used regardless of whether or not a supposedly "tubeless tire" is being fitted to the oem wheel.

Let's say that an owner for whatever reason decides to ignore the FSM's instruction to use a tube, and mounts a tubeless tire without a tube onto a wheel that isn't designated for tubeless application. Such owner has imo increased the risk of incurring an instant deflation.

Other things equal, seems logical to me that hitting a bump hard enough to push the tire bead away from the rim edge would be more prone toward allowing instant deflation without a tube than with a tube.

In any event, I'm not prepared to assume that simply mounting a "tubeless" tire renders obsolete all of the instructions in all of the FSM's about using tubes in the oem wheels.
I've not yet seen an FSM that says a tube is required with the oem wheel except when a "tubeless" tire is fitted to the oem wheel.

For that matter, is it even possible nowadays to buy a new motorcycle tire that isn't marketed as a tubeless tire?

Here's an excerpt from the FSM Supplement which covers the 1976 KZ900-B1 LTD model (which came stock with genuine Morris Mag wheels).



"Bead protectors" probably refers to spoke wheeled models' "rim-locks" not being used with the Morris Mags. I'm unfamiliar with the mentioned "service tool" available from the Kawasaki Parts Department.

I believe the following photo shows a raised ridge in the rear wheel rim of the Morris Mag (which came stock on the 1976 KZ900-B1 LTD model), and which may be the "special design" referred to in the FSM excerpt:



Yippee! :woohoo: -- raised ridges AND tubes.

Perhaps another reason for using tubes is porosity of the aluminum in the rim structure whereby air pressure might gradually escape.

Good Fortune!

That Morris wheel is the first I've seen that was tube type and had the ridges. I've never seen a Japanese wheel that way.

So again, some of the earliest tubeless KZ and GS wheels didn't have the extra ridges. I'm 99% sure those wheels are identical to the tube type wheels EXCEPT for the machining of the valve stem hole. Modifying a tube type aluminum wheel to accept the tubeless valve stem effectively duplicates what the factories did and allow use of tubeless tires.

A tubeless tire isn't going to catastrophically deflate when hitting a bump because the extra humps are not present. If that was a risk then how come Kawasaki and Suzuki sold bikes with such wheels?

For the sake of argument let's assume you have two wheels, one with a tube and one tubeless, and neither have the extra ridges. Now we have super low air pressure, say 8 psi, and the bike slams into a large pot hole.

According to your thinking the tubeless tire will move away from the bead, the tire will get all wobbly, and the last 8 psi will immediately exit. When the tube type wheel/tire hits the same pot hole the tire will similarly move inboard and come away from the bead and start wobbling, just like the tubeless wheel, however that 8 psi will remain. Do you think that small amount of air is going to keep the rider from crashing? I doubt it.

Thats not so much a raised rib as the center part of the rim is deeper.In the research I've done regarding this matter I found that tubeless rims have a deeper rut running the inner circumference,like the one in the picture.In my case you can see the tubed rim has a shallower,the rear tire is deeper.I believe that Morris mag you show is a tubeless rim

Nessism wrote: ..........So again, some of the earliest tubeless KZ and GS wheels didn't have the extra ridges.......

As you say, this is true of the earliest tubeless wheels. However, later wheels have the ridges. There must have been a reason for those ridges to be added to the wheels. Is it possible the reason was related to problems of tires deflating quickly? I doubt we we ever know for sure since it is unlikely Kawasaki would publish anything documenting such a problem if it existed, but since those ridges are not cosmetic, it's unlikely that Kawasaki made that change without a reason. Ed

All I know they're a Bitch to change, :pinch:
Steve

To perform an experiment, let's say we have in hand a motorcycle wheel with mounted tire (no tube), and another matching motorcycle wheel with mounted tire (with tube) in hand. No raised ridges.

Inflate each to say 20# psi.

No tube -- Use a tire tool to push the tire bead away from the rim. I'll bet the tire deflates.

With tube -- Use a tire tool to push the tire bead away from the rim. I'll bet the tire doesn't deflate.

Extrapolate this thinking to a rock instead of a tire tool that pushes the tire bead away from the rim while heeled over in a curve.

This isn't the common "hitting a pothole" scenario where the rider is shaken, but otherwise remains stable and upright, and likely retains control. Perhaps neither tubed nor non-tubed would deflate. Simply hitting a pothole isn't the issue. And would likely not result in loss of control even if one or both tires did deflate from being destroyed or due to rim damage. As to deflation due to rim damage, I believe a tubed tire would have the better chance of remaining inflated.

The perceived risk is the less common scenario of hitting a bump while heeled over negotiating a curve, when balance and control is more critical. And where tire deflation is imo more apt to result in complete loss of control.

And just for fun, repeat the experiment using wheels with raised ridges. Good luck with pushing the tire bead away from the rim, whether tubed or non-tubed.


Tons of research and testing exist with regard to physical shapes of wheels where the tire bead meets it, wheel contours, bead profiles, dimensions for all types of wheels, including motorcycle wheels, etc, ad nauseam.

Here's just a sample:
www.carbibles.com/tyre_bible_pg4.html
www.carbibles.com/tyre_bible_pg4.html#rimcontours
www.carbibles.com/tyre_bible_pg4.html#humps


As I recall, back in the day, it was a big deal when motorcycles finally caught up with automotive technology and began the adoption of tubeless tires.

I suspect and would hope that the motorcycle wheel designers considered the best wheel rim shape for tubeless tire application, and didn't decide to just bore a larger hole in the earlier tube-style wheel rims to accommodate the larger tubeless valve stem.

On the other hand, maybe it had everything to do with advancing motorcycle tubeless tire technology, and nothing to do with motorcycle wheel design. But the motorcycle industry seemed to proceed cautiously in this regard. And obviously decided somewhere along the line to eliminate the raised ridges or to at least minimize them.

Meanwhile, I've never seen anything from a motorcycle factory saying or implying that it's okay to ignore FSM tube requirements by just reaming out the valve stem hole.




. . . but there's enough doubt to keep me me fitting tubes on oem wheels when the FSM specifies using tubes.

Good Fortune!

650ed wrote:

Nessism wrote: ..........So again, some of the earliest tubeless KZ and GS wheels didn't have the extra ridges.......

As you say, this is true of the earliest tubeless wheels. However, later wheels have the ridges. There must have been a reason for those ridges to be added to the wheels. Is it possible the reason was related to problems of tires deflating quickly? I doubt we we ever know for sure since it is unlikely Kawasaki would publish anything documenting such a problem if it existed, but since those ridges are not cosmetic, it's unlikely that Kawasaki made that change without a reason. Ed

The ridges are a safety improvement. No doubt. But this improvement would affect tube type wheels just as much as tubeless.