‘73 1800ES - I’ve got a few original steel wheels that I’m slowly getting around to stripping the old tires off of, sand blasting, repainting, and mounting new tires on. I found a couple of the old wheels to have inner tubes, making me think a previous owner may have installed them due to leaking rims. I know from personal experience that the spot welds can be a source of leakage. I prefer to not have to use inner tubes with the new tires, so I’m in search of a sealant that I can apply to the inside of the rims, over the spot welds. Someone suggested applying Flex Shield over the spot welds which “sounded” like a good idea but I’m not sure if that’s a good plan or not. I don’t want to have to remove the tires if the Flex Seal turns out to be a bust. Is there a particular sealant that is known to work well for this purpose?

Thanks to you all for taking the time to share your thoughts. Actually, since my original post, I had revised my thinking from using Flex Seal to using something like rubber cement. I think contact cement, being a close cousin to rubber cement, would be an even better option - great adhesion plus remaining flexible for a long time. Internal air pressure will be my friend, however I see centrifugal force being an enemy. I had even thought about applying some to the shoulder of the valve stem to better my chances of an airtight seal there. I couldn't believe Dave suggested that also!

So, besides the four wheels that are still on the car with rotting tires mounted, I have three spare rimes, which will be sand blasted, bead sanded smooth, and painted silver, just like the four on the car. One of those spare rims will get a new tire mounted and balanced just like the four that will be on the road. The other two spare rims will sit in my shed looking pretty until I hit a good ole' Atlanta pot hole or clobber a curb and need to replace one on the car.

I belong to a small automobile hobby club where have a sand blaster, a tire mounting machine, and a computer balancer, among other equipment. I have already stripped the old (maybe 25-30 years old) tires from all three spare rims and started the clean up process. I put each tireless rim on the balancer and ran it by itself to verify trueness and balance before wasting my time mounting a tire on any of them - all look good except for my concern about finding inner tubes within them and wondering about possible spot weld leaks.

Per Derek's comments I compared the valve stem hole diameter on all three spares in addition to the ones still on the car. They all seem to measure just a smidge under 1/2" diameter so I believe the 0.453" dia x 1-1/2" long valve stems that I purchased from Amazon will be a good fit. It was encouraging to find the wheels on the car have tubeless valve stems, leading me to believe the rims don't leak. I think I still want to coat the spot welds with contact cement just to make sure there's no leakage.

Hi Chris,

Especially if you're in the salt belt like me in Boston, you might consider
painting with cold zinc (90% zinc) after sandblasting.
It's the next best thing to hot dip galvanize.

I've been using some old steel 740 rims for snow tires and full size spares here and Rustoleum spray enamel is only good for a few years.
I'll use the cold galvy next time I finish a steel rim.

Good luck, Bill

Chris, I had that problem many times with the old sport rims. Give the middle area a good clean and paint the weld areas with a couple coats of contact cement. Learned that from a tire jockey. In addition to being glue, air pressure and centrifugal force will keep it against the rim and into the microcracks. At the next tire change it was all still fine, just aged brown. I also did the base of the valve stem. Cheap easy fix, best done at a tire change.

I also find the tire shops mostly do a minimal cleaning of the bead area, another area for slow leaks. I usually take them home for a proper cleaning (softer fine brass wire wheel) and bring them back the next day for mounting and balancing. I'll even sand and repaint the lip if it's really bad or any hint of bare metal.

BTW I'm now a big fan of paying extra for a dynamic load balance. More and more shops now have these expensive machines. Those machines tell you when it can't be balanced within spec, whether it's the rim or the tire. If it's the tire, get a note on the receipt that you can use for warranty replacement. Done that twice now and these were decent brand tires. There was a small vibration at only certain high speeds on only certain road surfaces. Moving the wheels back/front proved it was the wheels, brand new at the time. The original tire shop rechecked and said they were properly balanced.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Probably best not to waste time and money on rims that do not have a safety bead. These are for tubeless tyres. Earlier rims which used tubes are still fine if you mean to use tubes. These rims will have a larger hole for the valve as it is part of the tube. Current standard valves are too small for these but you can get larger pop in valves to convert the rims. It will mean no safety bead, so use at your own risk. The safety bead also keeps the bead from moving around a bit which in itself can cause loss of pressure over time. The early solid wheel was never made with a safety bead a far as I know. Early perforated rims also had no bead but the part number wasn't changed when the safety bead was added. The bead can be seen when there is a tyre on the wheel.
A good coat of paint will seal the rim if rust free. Soft paint will tend to be seal better due to the pressure so enamel likely better than baked 2 pack.

Hi,

I would be afraid that using an elastomer compound would not be any better than the rubber tube or even worse. I’m saying if the rims are not suitable for tubeless tires you may be correctly concerned.
Besides I have never seen that any Flex Seal product seals out anything but water and shown without anything more than static pressures applied.

The rims are probably made of rolled steel into a band and welded across the butt ends along one area.
The center portion like the spokes would be welded to the inside of the rim so I doubt the welds penetration goes through from the inside to the out side where the tire is.
I agree that Spot welding is resistance welding.
Some with or with out fillers but in those cases it is considered skip welding too?

Some steels used in manufacturing rims do not take kindly to just any welding processes either.
You will need to know what steels are there before welding. Acid testing can help with identification.
You don’t want to end up with a stress crack.
Especially within the center bolt circle.
Cracks can develop from one bolt hole and going to the next bolt hole.
A lot of stress flow travels through the center structure during Acceleration, Braking and Turning.

The older bias tires of the fifties and sixties used tubes but tubeless tires were on the shelves by the seventies in upper grade brands.
You had to go a ways to stay with tube type tires eventually.

If you use anything an epoxy or urethane coating is probably advised to be best for longevity.
Both have greater adhesion properties than plain enamels.
Rim rust is probably the number one thing affects a tires bead sealing capability.
A Garden tractor, cart or wheelbarrows tires always seem develop a slow leak but then it’s also goes back to the rubber casing material.
The idea of a Flex Seal product just doesn’t blow a skirt up to get me interested.

Recapping of tires was more popular back then too but installing tubes was like a standard procedure using them.
In those days you could use hot patches or heat vulcanizing on tubes. Later on put adhesive boots were used inside of tubeless tire after a puncture.
Then even plugs came out for the new radials that allowed repairs for flats to be done without removal of the tire.

Somewhere along in all this the tires started using safety bead rims and tubeless tires, won hands or thumbs down, against tubes.
So these tires you found on those rims must be relics!

How old do you think the tires are? Any tubes are hard to procure today even for wire spoked motorcycles.
Maybe there is a solution for those rims that you can get for yours?

DOT requires decent labeling any more.
I can remember that manufacturing dates were not used unlike today.
Even If there were dates they were letters that seemed like a secret code.
Hopefully you have numerals. Consumer tricksters caused the DOT to go to numbers.
If you don’t have them, throw away the tires.

Phil