120 Psi To Seat Tyre Onto Rim - Damage ?
Discussion
I took my wife's freshly power coated OEM alloys and new Falken Winter tyres to be fitted today.
The tyres simply wouldn't seat (pop) onto the wheels after having them on and off a couple of times and coating everything in the lubricant they resorted to pumping them up to 120psi.
As the tyre didn't explode and there is no obvious damage am I correct in assuming no damage has been done ?
The tyres simply wouldn't seat (pop) onto the wheels after having them on and off a couple of times and coating everything in the lubricant they resorted to pumping them up to 120psi.
As the tyre didn't explode and there is no obvious damage am I correct in assuming no damage has been done ?
I've noticed there being a 'maximum PSI to seat beads' message on some tyres. IIRC most of the time it is amusingly low like 50PSI (which is nothing if you've got a stubborn, low and hard side profile tyre to seat).
100 psi is where I personally back out and will reseat a tyre. Never had any issues going to 100PSI, and I'd imagine 120PSI would still be fine. Makes you wonder when they'd have admitted defeat though. 150, 200PSI? The capacity of their compressor
100 psi is where I personally back out and will reseat a tyre. Never had any issues going to 100PSI, and I'd imagine 120PSI would still be fine. Makes you wonder when they'd have admitted defeat though. 150, 200PSI? The capacity of their compressor
This is from Uniroyal's technical data:
Uniroyal said:
When fitting tubeless car tyres, care should be taken to ensure that the tyre beads coming from the well-base first clear the hump in the rim shoulder.
To avoid cracks in the bead core, the "pop" pressure necessary should not exceed 3.3 bar.
If the tyre does not pop into place even at this pressure, the pressure must be lowered, and the cause identified and eliminated. Then the procedure can be repeated.
Only when the tyre beads are seated correctly on the rim shoulder may the pressure be increased to achieve the required press-fit and firm grip on the rim flanges. However, this "fitting pressure" should not exceed 150% of the max. pressure given in the tables or be more than 4.0 bar.
I would assume most other tyre brands will have similar recommendations.To avoid cracks in the bead core, the "pop" pressure necessary should not exceed 3.3 bar.
If the tyre does not pop into place even at this pressure, the pressure must be lowered, and the cause identified and eliminated. Then the procedure can be repeated.
Only when the tyre beads are seated correctly on the rim shoulder may the pressure be increased to achieve the required press-fit and firm grip on the rim flanges. However, this "fitting pressure" should not exceed 150% of the max. pressure given in the tables or be more than 4.0 bar.
Once upon a long ago a tyre fitter tried to seat a tyre onto one of my wheels by just keeping on increasing the pressure. Eventually the tyre burst with a gigantic explosion, hurling rubber all over the place - fortunately nobody injured. 
Leaving that aside, I wouldn't expct over-pressure to damage a tyre. They undergo enromous forces and survive in day to day driving. For instance when hitting a kerb or pothole.
Leaving that aside, I wouldn't expct over-pressure to damage a tyre. They undergo enromous forces and survive in day to day driving. For instance when hitting a kerb or pothole.
I've seen Max Seating Pressure before at 75 and 85 psi.
These winter tyres just have Max Pressure 40psi on them.
It seems they regularly hit 100psi but were getting worried over that.
Though one fitter said he'd gone to 150psi (max of the compressor) earlier in the week.
In fairness at 100psi they got the manager and they had removed and re lubed the wheels already.
He then said to me that the only way he knew was to increase the pressure but it was at my risk as I'd taken the tyres into them (they take the risk if they supply the tyres)
These winter tyres just have Max Pressure 40psi on them.
It seems they regularly hit 100psi but were getting worried over that.
Though one fitter said he'd gone to 150psi (max of the compressor) earlier in the week.
In fairness at 100psi they got the manager and they had removed and re lubed the wheels already.
He then said to me that the only way he knew was to increase the pressure but it was at my risk as I'd taken the tyres into them (they take the risk if they supply the tyres)
My local independant tyre fitter hates Falkens for this very issue. They always need over-inflating to seat on the bead, despite plenty of grease on the tyre and the rim. As they're all I fit to my daily drivers and I buy them from Camskill he doesn't tend to smile when I turn up. It is £50 cash in his pocket though and he hasn't turned me away yet.
I've never had to use more than 40psi, and I'm very surprised that going up to 100+ is often necessary. I've never fitted particularly low profile tyres or runflats though.
ETA: if the beads don't seat by 40PSI, I remove the valve insert and try again. Usually the more rapid inflation does the job.
ETA: if the beads don't seat by 40PSI, I remove the valve insert and try again. Usually the more rapid inflation does the job.
Edited by HustleRussell on Saturday 10th November 18:25
Sounds like someone was a little enthusiastic with the application of the new finish.
There could be untold internal damage to the tyre carcass and beads so there's no way on earth I'd want to drive on them.
In addition, the tyre fitter is a moron (like that is a surprise) for inflating to that pressure. Pop around and tell him.
There could be untold internal damage to the tyre carcass and beads so there's no way on earth I'd want to drive on them.
In addition, the tyre fitter is a moron (like that is a surprise) for inflating to that pressure. Pop around and tell him.
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