Originally Posted by Bill84:
Just how much air pressure are people using to air tires? Doesn't seem to me like 10-15 lbs. would create that much havoc. Not like putting 120 lbs. in a semi tire.
I have been up to 25 lbs to get the bead to seat. At that pressure the total force on the sidwall is about 17,000 pounds
Originally Posted by Rhody:
I have been up to 25 lbs to get the bead to seat. At that pressure the total force on the sidwall is about 17,000 pounds
That's about where I get really nervous, just because that's the number on the tire, it doesn't say anything about the integrity of the wheel, I've had new ones, that were cracked, from the factory, something goes a little off kilter in the forming process, the material is compounded wrong, doesn't take much, I know this, it to me, is more nerve wracking than driving the car, that's relaxing. JMHO! Bob
"Being old, isn't half as much fun, as getting there"! Ole Robert I!
Ask my brother John... He was mounting a front tire a few years ago. It had a tube in it and he was adding air and holding the valve stem. At about 10 PSI the wheel came apart and broke both bones in both forearms. I had never seen anyone physically turn gray before. As they were casting him up I asked him how he was going to paperwork his backside. The nurse said a good brother would help him. The brother said " I will get what I can with a water hose". Thank goodness his lovely wife was there for him...
If they won't pop on at 25 I leave them in the trailer for the trip to the track all pressed up. They have always popped on by that point, but the size is probably all screwed up by then.
Tires were my job on the team, before setting tire on rim I checked for spots the tire bead could hang up on & if needed file them down. Before beading the tire I'd spray the snot outta the area the tire had to slide over. Thought about getting some of that gel Docs use when checking yur prostate, man that stuff is slippery If tire didn't bead up by 20lbs I took it back down & lubed it some more
Originally Posted by t_inmyface:
I’m assuming he knows the area of the tire. If my memory serves me pressure = Force/area.
Yep- Quick and dirty math- Area of a 105" circumfrence tire is 877 sq in. Area of a 15 in rim is 177 sq in. subtract the two, 700 sq inch sidewall times 25 psi= 17,500. We can anlalyze the crap out of the forces, but suffice to say, it is significant. Here in California a driver died a few years back when the rim let go. It happened at the track.