MTFCA Forum

It took awhile but I finally finished the analysis of my tire slippage problem.
I have put together my findings in the attached document.
I believe there are two issues in play.
One with the wheels.
One with the particular tires that I had.
let me know what you think.

Bob

that is some thorough analysis that is often lacking on these pages. Kudos to you for a nicely researched and presented paper.

Thank you for your hard work! I am planning on a set of McLaren wheels as well, and I had an issue with T drivers and rubber stemmed tubes, they even slip on Ford rims... at least they did on mine. I'm curious to see how the profile of the bead on the Blockley tires measure up...

Bob
Very well done. Your logic and analysis is perfect.
This problem has been around for many years it is good to have someone finally determine the exact cause of the problem and come up with a solution.
Congratulations.
Ron Patterson

Bob- thank you for posting that! I do find it curious though, as I've had 30 x 3 1/2 Buffalo wires on my touring going on 20 some odd years and probably have over 50K miles on it in that time, worn out two full sets of T drivers and have never had a tire creepage problem, and I know that two of the rims came from John back when he 1st started selling rims and way before he started making complete wheels. Have always run flaps and keep the pressure between 55/60 psi. The rims are wrapped with polyethylene pipe tape as I've found that duct tape degrades over time and the adhesive turns to powder.. Just another data point I suppose. Please keep us informed!!! Dan

Good Job, BOB !!!

Well done Bob. Truth is always the ultimate goal. I have watched this problem as it moved around in my own chapter of the T club. I remember a new guy that bought 4 new rims and had them re-spoked right off the bat as part of his 1914 Touring Car restoration. He ended up going back to the wheels he had on it to start with. He was ticked to say the least. He passed away a few years after that and I don't know where those wheels went but my guess is he never got rid of them since he was not the kind of guy who would have passed them on.

Excellent work Bob. I have had no such problems with Universal T Drivers on standard clincher rims. It may be due to my use of rim liners rather than flaps. I cut a 2.5" wide strip from the outside diameter of a used 13" inner tube. This band is a snap fit on a 23" rim. It extends under the foot of the tyre and will help to fill the gap your research shows. Thus there is more contact between the bead on the tyre and the rim/liner.

I expect that this problem will not eventuate with the Blockley tyres becoming available. Info on their website makes really interesting reading.

Allan from down under.

Hello,
I have not been able to view the PDF download/analysis. I bought the McLaren wire wheel business from John a few years ago and have produced many sets of clincher style wheels since. When I build the wheels the final step I take is the purposely applied knurling to the inside edge of the clincher rim on both sides of each rim. When the tire is installed and they are properly inflated they absolutely will not slip. That said I have had customers contact me to ask why the inside edges seem rough when the rest of the rim is so nice. One customer actually sanded the knurling off before contacting me. I now mention the knurling in a helpful hints insert and also point it out verbally to patrons. I also had a customer who had a slipping problem with only one of his four wheels. He remounted the tire and immediately found that a large amount of tire mounting lube had somehow become trapped inside the tire. He cleaned it out and remounted the tire and no problem since. Proper inflation is definitely something to watch carefully since most new tubes seem to slowly leak air. Seems like I loose 5-10psi in mine over a 2-3 week period on my own wheels. Hope this helps. Thanks, Mike

I never put much thought into the subject of rim profiles, as I have always been under the impression that the reproduction rims available in recent years were made to original Ford prints. I have seen reproduction rims made in the 70’s that were of thinner material and clearly different profiles, but thought those times were behind us.

I pulled a really nice original non-demountable, a McLaren, and a New Zealand rim to compare the profiles against one another. Due to the (undoubtedly many) variations in original parts, I make no claim that this original rim is “correct” in any way. I also do not have access to the Ford drawing.

First is the original rim. The bead section blends from the flat center at roughly 1/2” radius to the widest point, then wraps the remainder at 9/32” radius

The McLaren has a similar 2 radius profile, but starts with a smaller 3/8” radius, and wraps with a larger 11/32” radius

The New Zealand rim has a more complicated profile that starts with a 20-30 degree angle, then a 9/32” radius peak, and a 3/8” radius return

So in conclusion... I have come to no conclusion!

I don’t believe that the original rim manufacturers were any more consistent than what I have shown above, and I suspect that the modern/original tire manufacturers have/had similar inconsistencies as well.

Did like the investigation detail and the process, well done.

Most times the issues with slippage is flakes of rust, undercutting the clincher curve, leaving sharp clincher rim. With edge less than the 1/8" smooth rounded thickness, lets the tire casing gets rim cuts and can slip or worse.

The only Ford print located is this one, early clincher rim, 3 1/2", plain rim for wood felloe.

Close up of print, posted years ago on forum.

One thing everyone is overlooking , are the rims powder coated ? Powder coating can be very slick .
A Museum I worked for, had this problem on a 1911 RR Ghost ,
I kept telling them it was the powder coat & they didn't believe me , 12 inner tubes later they relented.
I masked the rims off & had the tire side of the rim lightly sandblasted , and guess what , no more inner tube problems .
I learned this when I helped a friend that had the same problem with a set of 30x3 1/2 Buffaloes , that's how we fixed them !
Just sayin '

Well said Pete, but until you have to change the tyre, just put more air into the inner tube 10lbs at a time until the inner tube stem remains vertical. I run my T drivers at 100lbs on a 1500Kg English Crossley to cure tyre slippage....N.

Thanks Peter for the photo of the tyre/wheel(front).
You will notice the inner tube valve stem at the 7o'clock position is at 90 degrees to the rim and is pointing to the hub. 80 psi was required to stop the tyre from creeping on the rim.
100psi stops the rear tyres from creeping which I think is due to the braking forces. ....N.