Drove a short "tour" in my `24 touring, yesterday and for the second time (same rear tire) sheared the valvestem and caused a loud BANG as the tire went flat at around 35MPH. The first time it happened, lost the tire off the rim--but not this time.Last time I checked, I was running 50PSI on these 30X3.5 demountables.I`m wondering if tire pressure might be the problem or possibly those THIN chinese tubes, or even sharp edges where the stem penetrates the wheel? Anyone have similar experience? thanks, Paul
I run 55 to 60 pounds tire pressure on my 30 x 3.5 tires an have no problems
Are you using flaps? What condition is that rim in? Have you tried rotating the demountable rims?
Pictures would help.
I run 55 psi, but others run higher.
Neil
You mean like this?
This happened last Friday. I never did find the tire. It's still somewhere in the Johnson grass or the wheat. The position of the rim liner and the lack of a stem tells me this was probably due to low pressure, so now I'm making sure I have 65 psi all around before I go anywhere.
When you mount the tire the stem must be perfectly straight. The rim must have no sharp edges around the hole, and you must maintain at least 55 lbs. Since it was the stem that sheered off, it would appear to me that one or more of the above was to blame.
Norm
If you use powder or other lubricant for mounting the tire, maybe you should try something else.
Also, what surface is the clincher gripping? My rims are all polyester powdercoated, and I've never lost a tube to slippage - even down to 20 psi on a front tire with front brakes.
I learned from Jim Guinn the easy way to center a tube: deflate it, and roll the wheel in the direction the stem is pointing until it straightens up.
rdr
Ricks, Great tip! Thanks for passing it along.
Common cause is too little air pressure. That will let the tire shift on the rim shear a rubber stem.
1908 Motor Car Tires booklet
30 x 3/2" clinchers should be run with min. of 60psi or 65psi in the rear tires.
Rubber stem valves need to fit secure, they are tapered in length to help provide a wedge fit.
Metal stem valves are threaded and lock to the rim and felloe to provide more security in shearing than rubber stems.
Rubber stem is helped with support of a thick felloe, when in a demountable rim, flaps can assist in providing stem security in twisting of the tire revolving on the rim or hard braking, esp. when air pressure is low.
Steve, Did you cut your own rim liner? To the right of the valve hole on your photo it looks like the liner was not covered by the feet on the clincher tyre. This may have been the cause of your flat as the tube was caught between the edge of the liner and the tyre bead and was chafed.
When I cut rim liners from 13" tubes I make them 2.5" wide so that there is no chance the tube will contact the inside of the rim. Tubes are so thin these days there is no problem with the tyre beads still fitting into the clincher rim with some of the liner under the bead.
Hope this helps.
Allan from down under.
50 PSI you will cut all the tubes in short order. Proper tire pressure for 30 X 3 1/2 tires is 65 PSI. Problem solved.
Paul Griesse:
You need 65 lbs in the back tires. If you stop and think every time you put on the brakes you have pressure going one way on the tire and every time you use your low pedal you are putting pressure on the tire the other way. You are putting pressure on the back tires back and forth, back and forth, back and forth all day long. No wonder the tire and tube eventually moves and cuts your valve.
Steve,
Is the wheel rim bead sharp?.....it looks sharp in your photo. Sharp rims have cut tire beads resulting in blow outs.
I have used full tire flaps on my 1910 2cyl. REO since 1978 and no flats to date. Also am running full tire flaps in our 13 T for approx. 14yrs....not the bicycle style which are shown in your photo and no flats except for a slow high pressure tube stem leak which was repaired using two loops of lock wire.
Suggest you do not run sharp rims against a tire unless some added protection is provided.
I run 55 in clinchers, and try to catch them before they get down to 40, but sometimes they get lower. I mount them dry, so there is no lube to let them continue to slip.
rdr
Les, the possibility of a rim cut occurred to me. If I ever find the tire maybe I'll have a better idea of what happened. This rim isn't as bad as some I've seen, but I don't intend to use it again. I have some better ones I'm going to have galvanized to use on this car.
Steve Jeff:
Les Van Nordheim is right on. Anyone that does not use the FULL SIDE TO SIDE FLAPS takes a chance on cutting their tubes. The cuts not only happen from the sharp edges of rims but also for awhile Firestone Tires were so sharp on the beads that they were also cutting tubes.
Adding to what Dave shared.....For a number of years, I would not buy Firestone clincher Tires because so many T owners in my area were having tire bead failures with that brand. By comparison, there is only a small cross section of rubber/fabric where the bead connects to the sidewall. A tire is no stronger than it's weakest point.
Having sharp rims would enhance the possibility for tire bead failure especially using the older Firestone clincher tires.
On my new Firestone clinchers 30X 3.5 it is marked on the sidewall "inflate to 55PSI cold", now if i have a problem with 65# what does my five year warranty do.?
Rick
Rick
Check your sidewall marking again....my new 30 x 3.5 Firestone states 65 psi.
In my experience, the slipperiness of the rubber against the clincher rim is more important than inflation.
In my experience in 1999 with the last of the pre-1999 Firestone production, they were too old and too small, and I could hear cord breaking as I was mounting them. They didn't last much over one year.
rdr
Dan you are right, i had to put my glasses on ,get the magnifying glass and a bright light to make out the"6" to my bad naked eye it looks like 55.
Thanks for the information.
Rick
Honestly from Dan Treace's photo (re-posted below) the valve stem doesn't look like it's held in the rubber really good. That's just my opinion.
The reason the stem is not held to the tube very good is because the nut hasn't been tightened yet! Whatever Dan says, pay attention! Don't buy those vulcanized stems either. They aren't correct, not only that they are too big.