TR4/4A Dangerous Experience to Share

[KVH]

Some of us never learn except by the error of our ways.

I turned a corner quickly today in my newly tuned 4A, enjoying the warm weather, and pulled my tire beads right of their seats. The wall of my tire was quickly sliced up by my rim, and at only 40 mph the sound and ride made me feel like I'd lost an axle. All this in rush hour traffic. I was soon limping along with a heavy thumping (the source of which I'm still uncertain) at about 3 mph, finally made it into a right lane, and then another 1/4 mile to a Church parking lot. The fear of being hit from behind by vehicles traveling well over 50 mph will stick with me for awhile.

I'm sharing this story because I've never had anything like this happen since I lost a ball joint in the 70s. But today was 100% my fault. I was deliberately keeping only 22 pounds of pressure in my Kumhos, but even at that I'd failed to check pressure for over 6 weeks. My guess is that with the passage of time I had somewhere around 18 pounds in that tire.

Now I know why it's said that tires should never be under-inflated. My mistake was assuming that a light car could take a lot less air. The fact is that the specified pressure is necessary to keep a tire properly seated and beaded. I assume if I'd had Michelins my story would be the same (but in a way, I wonder).

Anyway, I'll next pull my spare tire back off and examine what damage if any I caused. I have Goodparts CV axles back there, and I'm hoping this didn't cause interference with the trailing arms.

 

[GTP1960]

Thanks for sharing that wisdom. I don't check my pressure often enough.
glad to hear you made it to a church lot without further incident.

 

[PeterK]

Better to make it to the church in a limping TR than in a pine box. Good you're safe.

 

[TomMull]

The lesson is to check the tire pressure regularly. Although I don't think there is anything wrong with keeping them at 22, they'll wear more quickly, require more force to steer and if anything like my 3, handle poorly, but they shouldn't fall off the rim. My guess in you case is that the tire probably didn't come off because it had only 18 pounds, but rather had a serious defect, hit something or was way under 18 pounds. Your experience sounds much like an old fashioned "blow out", quite common when our cars were new and almost always caused by damage or defect, but thankfully very rare now with today's greatly improved tire design and construction.
Tom

 

[HerronScott]

We always had wire wheels with tubes so never had that happen on the Triumphs but I had a 1987 Mazda 626GT where it happened twice several years apart (different wheel each time) with the first cold snap and while cornering. It did seem to just pop the bead and after refilling with air no further issues with the tire or rim. I attributed it also to extremely low tire pressure and did a much better job keeping an eye on it after the second time.

Scott