Let's talk tire tube valve stems.......

W

w30bob

Well-known member
Howdy Boys,

I'm sure you've noticed that on the front rims of Cubs the most damage inside the rim is usually right around the valve stem. Water makes its way in between the stem and the rim and then sits there and rusts the rim from the inside out. When I took the old original tires and rims off my '77 I noticed that the Firestone tubes had valve stems with a rubber coating on them that was a tapered column, wider at the base and narrower at the top where the cap threads on. There was also a horizontal cutout where the rim intersects the valve stem, essentially catching the valve stem and not letting in any water. It also stops you from easily removing the tube, as the valve stem is essentially locked to the rim.........so I had to cut that portion away with a knife to remove the tube, but it's a good idea. Unfortunately not a great idea, as my rims did have some rust right there on the inside where the stem pokes thru. I then looked at the new China junk tubes that came with my new tires and those valve stems are perfectly straight.........which will allow even more water to get into the rim at the stem and sit there between the rim and the tube. I've blasted and POR-15'd my rims, so the water won't rust anything now....but I got to wondering if there was something that could be put on the valve stem to make it waterproof and not let water get in around it. Has anyone found a good trick to deal with that issue?

thanks,
bob
 
No ideas on the water but there is a plastic bushing that you can put on the valve stem to help protect and keep it centered. Available at most tire shops. Installed on stem before tube is installed in tire and wheel.
 
You could check and see if the larger diameter valve stems are available from your local tire dealer. It is a matter of ordering a different style stem.
 
Hi Guys,

I checked out the types of valve stems and the tapered ones like those in my Firestone tubes are TR15. So far I've not found anyone selling 4.00 - 12 tubes with a TR15 stem.....they all have the smaller TR13 stem. I've checked Miller, Titan, Carlisle, TM, Hamiltonbobs, Firestone, etc. Seems the smallest tires to use a TR15 stem is a 4.00 - 15, not a 12. I'll make some calls tomorrow and see what folks say.

Thanks,
Bob
 
Hi,
It might not look too good, but some black rubber type sealer, in a tube, applied at the valve base, after the tire is on, and inflated, probably will seal the opening and keep water out.
Apply it with a finger, or a small screwdriver. It has to make good contact to the valve stem base, and the wheel, all the way around the valve.
 
w30bob":2ggh0nsk said:
as my rims did have some rust right there on the inside where the stem pokes thru. .........
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You've got a forty year old tractor, it's gonna rust a little in places.

I personally don't see Cub front rims rusting out as an epidemic. I also don't think a properly inflated tire is going to have major water infiltration for it to rust. It will rust more where water can remain in the crack along the bead setting against the rim.

Now if the tire sets flat for years outside or you park in a creek...........

If you're concerned though, put an o ring on the valve stem before you insert it in the rim. If that's not good enough use a bead of black silicone and wipe off what squeezes out after you air up the tire.
 
Hi Guys,

I'm still looking for tubes with the TR15 stems but it seems they are now only made for 15 inch tires and larger, not 12's. Not saying rim rust is an epidemic, just an annoyance. Every tractor I own has had rust on the inside of their rims by the valve stem, where water gets in and sits.....so I just would have thought someone would have addressed it by now. Actually, the only reason I ever had to replace a tractor rim was because it was rusted thru from the inside out.......and I just won't trust a rim structurally if rusted thru. Of course tires and tubes made today don't last 40 years anymore, and I'd be surprised if these junk Chinese tubes last 10......so I will be checking it more frequently in the future.

regards,
bob
 
w30bob":r8g9bi8o said:
.....and I just won't trust a rim structurally if rusted thru.....
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Two factors come to mind: 1. Tires used in this application are probably never going to be inflated more than about 25-28 psi and 2. they are probably never going to excede about 12-15 mph so any flat resulting from a rusted rim is not going to be catastrophic. :hattip:
 
Hmmmm.............you guys don't have Engineer friends I guess. We tend to get anal about EVERYTHING......but I hear ya. In researching this further it looks like the original Firestone tubes don't have TR15 valve stems, they have TR13......but they've added a thin layer of tapered rubber that forces the stem into the rim stem hole with no wiggle room. Those Firestone guys were smart. Looks like a TR15 stem would be too thick for the rim hole as is. I ended up using HondaBond 4, a fantastic flexible gasket maker compound that Honda uses to seal motorcycle crankcase halves instead of a gasket, on the base of the stem. You can all rest easy now..........catastrophe averted!!! :{_}:

regards,
bob
 
w30bob":2yxna4ti said:
Hmmmm.............you guys don't have Engineer friends I guess. We tend to get anal about EVERYTHING.....
Click to expand...
I been a machinist in a job shop that does a lot of prototype work for over 22 years, I deal with engineers quite a bit. I learned a long time ago there’s a huge difference in theory and application :lol:
 
Hey, glad you brought this up, had to replace a front tire and tube recently on my 48 Cub and I do not like the stem to rim interface. The stem seems too small or the hole is too big. I was more worried that the tube moving around would get worn through on the rim, and I'll be back getting another tube. Will do something to cushion that area between rim and stem.
 
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