I would suggest that you use inner tubes with your new tires. While a person might conclude that a 1 piece cast wheel could be run without tubes, and some riders do that, the original specification was/is to use inner tubes, as you know. I think it is best to follow the vehicle manufacturer's recommendation.

Thank you both for your comments, this is the EXACT input I was looking for and is very helpful to push me towards going with Tubes

After this RT gets launched in the spring, there is an 84 RS waiting in the wings next and it too will need tires!

Cheers,

Ethan

I have run those tires on RS "snowflakes" both with and without tubes. Here's what I found...

> My first concern is the original concern... The snowflake was never designed to hold air. Is the casting porous (e.g. air permeable) ? And secondly, can tubeless tire Stems be fitted to the snowflake in an airtight manner ? The answer to both is well proven. The casting does not leak air at any appreciable rate and there are bolt-on wheel stems available that are able to seal to the snowflake. 

> My next concern was that more heat build up in a tubed wheel and would reduce the mileage from my tire. That didn't happen. For the guy riding "300 mile day trips" there was no discernible difference in tire life.

> My last concern was that a tubed wheel would need to be removed on the side of the road, whereas a tubeless mounting would allow a quick "plug job" to be carried out on the bike. I never picked up a nail or had a flat tire for any reason.

But here's what I did discover....

> Almost all modern motorcycle tires (especially the models with enhanced handling and braking) have the ability to be used "tubeless". It's simply cheaper and easier to manufacture motorcycles without tubes. While manufactured for tubeless use, any of these tires can be mounted with a tube. No harm is incurred if you add the tube.

> The snowflake wheel for all its strength and beauty in 1978, though a strange twist of fate, has in 2025 become a nearly useless dinosaur, or at least something in-need of some serious updating. Let me explain...

> What gives any tubeless tire its "tubeless ability" is the tighter sealing against the nominal portion of the wheel. That is to say, the inner diameter of the tire fits tighter on that portion of the rim. If it's a "19 inch wheel", then the sealing portion of the tire is that inner diameter that is exactly 19 inches with some sealing lips added... which may render it to finally measure 18.95 inches in the unmounted state. Whereas on tires BEFORE the "tubeless age", unmounted tires were more apt to measure 19.15 inches (somewhat larger). 

What the "pre-tubless age" designers of the snowflake did was to take advantage of this looseness and save money by NOT machining this 19.00 inch portion of the wheel. They simply cast the diameter and ended up with something close that worked great with the tires then available. Unfortunately, that cast portion ended up measuring at something larger than 19.00 inches. 

So what we have in 2025 is a wheel that sometimes measures 19.10 inches and a great many tires that measure 18.90 inches. In other words, the tire mounting person ends up with a supreme struggle to mount a small tire on a large rim. And this is all because modern riders want the handling and braking advantages of modern tires... even on their 45 year old motorbikes. 

(Let me state here that perfect rim sizing on "spoked steel and aluminum rims" is not a problem. They all measure a smooth and precise 19.00 inches. Anyone can mount tubeless tires on an R75 without trouble. The issue lies solely with the snowflake.)

> This small-tire-on-large-rim issue has to be confronted. If not, some shops may refuse to mount your new tires. They may stop halfway through mounting, leaving you faced with having to pay extra charges or walk home. I know of 2 cures:

- Use a silicone-based lubricant (like SuperLube) and up to 80psi to pop the bead out during mounting, OR (the permanent solution) have a machine shop turn and cut both snowflake mags to their true diameters. Popping a tire out usually takes about 35psi (max), but without this machining you may need to get up to a VERY dangerous 80psi. People get killed at that pressure.

- On the other hand, truing the snowflake up to modern dimensions will require a "gap bed lathe" which is an uncommon, specialty machine tool. And in my locale I could never locate a "job shop" that had one of these machines. 

So to sum up a long story... in my experience you will have problems, but they are not where you suspect. They are the strange and curious result of the bike being old enough to span both the "age of the inner tube" and the "age of the tubeless tire". 

Let us know what you discover as you work through this situation. I'd love to hear your results.

The other point is that rims are manufactured to hold the tire properly for a good air seal where old style rims were not. Despite people trying it out I would not recommend running what were specified as tubed rims without tubes.

I just went through this exercise purchasing a set of BT46’s. On the Bridgestone website, the info chart for the BT46 tires (most likely all of their tires) indicates if they are suited for “Tubeless”, “Both”, or “Tube Type” applications.

I purchased metric size tires. I had to buy the 100/90-19 H rated front, which was labeled “Both”.  The sidewall on the tire says “Tubeless - Use tube on tube type rims”.  The V rated version of the front tire is labeled “Tubeless”, and my contact with Bridgestone indicated if labeled “Tubeless”, they do not recommend using with a tube.  The 120/90-18 rear tire is V rated and labeled “Both”, so ok with a tube.

For those wanting the original inch size tires, things get weird. The 3.25-19 front tire is labeled “Tubeless”, which means Bridgestone recommends tubeless applications only.  The matching 4.00-18 rear tire is labeled “Tube Type”, so for application WITH a tube only. I say, that makes no sense. I responded to the Bridgestone rep telling him this makes no sense, but never heard back. 

I’m sure there are many, many 3.25-19 BT46’s mounted on spoke wheels, and snowflake cast wheels, with an inner tube.  But, Bridgestone would say NO.  I think they need to review their technical information, but that’s what they specify.

Too bad they didn't reply to you about that question. I agree it's weird for one to say tube and the other to say tubeless. Good to know as I need new rubber for my R65. 

Posted by: @4949

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I’m sure there are many, many 3.25-19 BT46’s mounted on spoke wheels, and snowflake cast wheels, with an inner tube.  But, Bridgestone would say NO.  I think they need to review their technical information, but that’s what they specify.

All the other 50 year-old motorcycles are being ridden as Classic or Vintage, and typically only pulled out of the garage for local m/c club show dates. And these guys are happy to mount and roll around on their vintage Dunlop K70 tube-type tires, because they are "period correct" for their vehicles. 

That squarely places the Airhead in a distinct and unique group of 40 and 50 year-old motorcycles that are actually used to ride hundreds of miles a day and need the advantage of superior braking and cornering that modern tires offer. This distinct and unique group probably represent about 1/2% (or less) of the motorcycle riding public. You never got a response from the tire rep because THERE IS NO correct response. As I had previously said your typical Airhead motorcycle falls right in the middle of the tube-type/tubeless cut-over era, and Airhead owners (unfortunately) are left "holding the bag".

I have been running rear tires for years either with or without tubes.  Lately without because of my perceived and hopefully never to occur belief that it is easier to plug a tubeless tire than it is to pull a tube on the side of the road. This is my opinion based on the few flat tires I have encountered in riding.   

That being said, the original issue from the dawn of time was BMW stated the snowflake wheels were designed to have tubes in the tire.  It was felt the tubeless tire could come off the rim or some such thing, easier than a tire with a tube.  I believe BMW snowflake rims lack the so called safety bead found on rim designed to use tubeless tires.   At this point it becomes a word filled discussion pro and con, yes and no, do or don't.  As I know it, BMW said don't use tubeless tires on snowflake rims.  

My last flat tire was with a tube in the rear tire and it was an absolute pain in the butt to repair.  The cause of the hole was an Allen wrench I didn't see and ran over.  Laying the bike on its side to pull the wheel was the worst part other than breaking the bead and pulling the tube.  That was 15 years ago and I am now crippled with worse legs and such.  So now I don't know if I could get the tire out to pull a tube.

LOL, I still carry a spare tube as well as a good plug kit and small compressor, because with my luck the next hole will be in the side wall where it can't be plugged. Or, it will be a simple plug and go.

I am much less worried about hitting something and destroying the wheel.  But I do run a tube in the front wheel because that is the rim that will be the most likely to suffer an impact and less likely to just pick up a nail and the front wheel is a heck of a lot easier to get off the bike than the rear.

Do I like going agains BMW's warning, not really but, I do so with fair warning.  This is the choice I make.  We are lucky we can still get tires to fit our bikes.  Like Richard says we ride our bikes we don't show them   I have a lot of miles on the tubeless rear tire and knock on wood, haven't had a flat in a bit.

Experts like Richard, Snowbum make good points but the choice is yours,  this issue has been discussed for a long time.  It is too bad we will never have a true tubeless rim to replace the snowflakes with.  Good luck with what ever you choose to do. St.

Thank you all very much!  I certainly got answers to my question.  FWIW, I am going with tubes front and rear.  

Cheers,

Ethan