Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Tire leaks when mounted, not when unmounted

Tire was losing about a pound/day. I swapped in the spare. I cleaned the leaky tire, inflated it to 39 psi (max 35), squirted soapy water all over it. I couldn’t get a single bubble. I checked at the rim especially closely, and the valve (last tire failure was the valve - different tire). It isn’t losing any pressure sitting in the bed of my pickup. To my inexpert eye the rim looks okay. I haven’t had the kind of accident that would hurt the rim, or run it on low pressure (I check the tires before every drive.) The tire looks okay except for some cracking that all my tires have. I bought it in 2002.

Not OK as we’ve tried to tell you again and again but you lack the capacity to understand this.

The air is likely leaking through the many cracks in the tire. The tires is string and rubber. Only the rubber holds air. Cracks let the air out. The bubbles may be too small for you to see.


Well, clearly we need to rule-out the trifling factor of dried-out tires that are now 16 years old…


I’m surprised your 16 year old tires are only losing 1lb a day.

I sometimes think you are suicidal, and then you go and post something like this and confirm it.

Driving on tires that are showing cracks is very dangerous to you and those around you.


A kid turns 16 and the kid is old enough to drive. A tire turns 16 and it’s old enough not to be driven on.
When the tire is laying in the bed, there is no weight on the tire so it doesn’t lose air. When the tire is mounted on the truck, the weight of the truck is forcing the sir in the tire out of the cracks in the sidewall of the tire.
I have had tires that lost pressure and nobody could find the leak. Even though the tires still had acceptable tread depth and didn’t have sidewall cracks, I replaced the tire.
One thing you might do in the interest of science is to put some sealant in the tire. Mount the tire on the truck, leave it for a day, then remove the tire. You will probably find out where the tire is losing air by where the sealant is oozing out. Please note that this isn’t a repair. Don’t drive on this tire as it will be terribly out of balance. I did this with a basketball that was losing pressure. I found the leak, but the basketball then dribbled worse than a bowling ball.


I don’t mean this to be snarky, but instead of figuring out how to overcomplicate an oil change, how about figuring out where you want to buy a new set of tires?

OK, maybe I mean it to be a little snarky, but c’mon man. You’re going to kill yourself, or someone else, driving around on that junk. Screwing around with thought experiments is one thing. Endangering everyone unfortunate enough to share the road with you is not OK.


As seen on TV!

Take the tire off, unmount it, paint the inside with a flex Seal, remount it and drive on!

Or get real about the danger you cause by continuing use of these tires and buy a set of new ones. Surely you can find a 4 for the price of 3 sale.

Edit: Did you miss the accident west of Albuquerque on I-40? A tire blew on a semi truck, it crossed the median, and hit a bus head on. Lots of dead people. Notice the similarity?

1 Like

I had a tire like that. Bubbles indicated no leaks when removed & laying flat on the ground. Only leaked when installed on the truck. I figured it out by painting soap bubbles to the rim area when it was mounted on the truck. I had to do that experiment several times, each time after parking the truck in a different tire orientation. I eventually saw where the leak was coming from, at the rim/tire interface. I removed the tire from the rim, cleaned & wire brushed the rim’s bead surface, and re-installed the tire using bead sealer. No leaks since.

I’m voting for a set of tubes just like in the old days. Then you can drive on with cracks in the tire until the tube starts to come through like a rupture (ouch).


Ha ha. I did this to an old snowblower once. Worked like a charm. But my blower doesn’t go on highway speeds and is reserved for driveway only.

Gotta remember back in the 50s everyone had tube tires on their cars. Then a little later you had the choice of buying the tube tires or the new fangled tubless tires. Not that long ago actually.

4 are 16 years old; 1 is 20 years old. Only 1 leaks.

When they turn 18 they can vote!

An unmounted tire at 39 psi is at the same pressure as a mounted tire at 39 psi (probably with less air in it when mounted.) To the extent that pressure is what matters the cases are the same. Bearing the weight of the truck causes the part on the street to splay, which would exacerbate the leakiness of cracks there.

I was trying to understand how cars work.


I don’t drive.

I’ll buy 5. Money is no object.

I don’t drive on the Interstate. My pickup weighs 70 tons less. I’m likelier to grind to a halt, destroying rim, and get rear-ended.

A useful response! Thanks Mr @George_San_Jose1 !

I’ve done this on my bicycle. It’s pretty exciting when a tube at 115 psi gets out of the tire.

Mostly we got car tubes for use in the lake (no one had a pool, not even the city, but we had lots of lakes. A neighbor worked for an implement dealer though so once in a while we’d get a huge tractor tube. Good for about four or five kids at a time. Actually the car inner tubes were a lot better than air mattresses. You just sat in them and could paddle all over the place or lounge, whatever you wanted to do.

I heard a BBC story about African immigrants crossing the Strait of Gibraltar in inner tubes.

I have to agree with everyone else. 16-year-old tires are dry-rotted and should never be used. Replace them before you kill yourself, and maybe others.

I had a tire nearly come apart on me once and it was scary. It was about 6 years old which is when the suggest replacing them. The tread looked fine but the overall structure of the tire failed.

It came on a used car and I didn’t think much of it. A guy at the gas station saw me on the spare as I drove it home and he asked what happened. I showed him the junk tire with steel showing and he was like "That is one of those Douglas tires from Wal-Mart, they all do that. I wasn’t real happy as there was another one on the car. It started to feel out of balance not too long after and I replaced it. The tire shop indicated that it was starting to come apart from the inside out. I guess “they all do that” as the guy at the gas station told me.

In my business I find that those who try to be cheap often spend the most money. That applies to many things. You try to skimp and pay big time!

1 Like

Another correspondent posted a picture of dry-rotted tires. Mine look nothing like them. The cracks are in the furrows of the tread; the sidewalls look okay.

Like ply separation? I’ve seen that.

I bought the highest-rated, most-expensive tires at Costco. They’ve lasted 16 years.

The 16 year old tires would have been fine during WW II. The national speed limit was set at 35 mph. This was done to save gasoline and save tires. In fact, part of the rationale for gasoline rationing was so that people wouldn’t drive as much, thus stretching the life of their tires. Rubber was scarce and needed for the war effort.

Quick poll… Is there ANYone here besides Random that doesn’t think he needs to replace these tires?

Anyone? Hello, anyone? Bueller? Bueller?

If he could put the tires in a time machine and send them back to the 1942-1945 time period, these tires would be acceptable for the National speed limit of 35 mph. There were fewer cars on the road.
For today’s time period, these tires are only acceptable for driving through a farm field.

1 Like