Safe tyre pressure?

[DaveReading]

After buying a track pump a few months ago, I found out the hard way not to inflate the tyres on my old steel-rimmed-wheel 10-speed to anywhere near the rated tyre pressure. Two blowouts in the space of a week, one nearly giving the pedestrian I was passing a heart attack, before it dawned on me that the steel rims had no bead to retain the tyre on the rim. Backing off the pressure by 15psi prevented a recurrence.

Fast forward to my 3-month-old EBC tourer (alloy rims, obviously). It came with tyres rated at 90psi, so I thought it would be safe to pump them up to 80. Then, out riding today, after 15 miles or so I became aware of a thump-thump from the front wheel. I stopped and saw an ominous-looking bulge in the front tyre, but before I could get to the valve to relieve some pressure there came the inevitable bang. I haven't taken the cover off yet, but I expect to find the inner blown to smithereens.

Granted, it was a hot day today, so maybe I should have allowed for that, but I'm now confused as to how much air I should put in my tyres so this doesn't happen again?

 

[Mo1959]

That's strange. Not something I give much thought to must admit. I always keep my tyres right up to maximum pressure and never had any problems. Be interesting to hear what others say.

 

[ColinJ]

Are you sure that you are fitting your tyres properly? This should be an extremely rare occurrence yet you have had it happen on two different types of wheel over the course of just a few months.

PS What I think is probably happening is that you are trapping your inner tubes between the rims and the tyres.

 

[Deleted member 20519]

Is it possible that the valve on your pump is giving you a lower number than what the pressure actually is?

 

[DaveReading]

Well I've been fixing punctures for nigh on 50 years, so I don't think there's anything wrong with my technique.

The only thing that's changed is switching from a hand pump to a track pump, hence the ability to put more pressure in.

And my tourer has the tyres it was fitted with when delivered, I have no reason to doubt EBC's ability to fit tyres properly.

 

[Cyclist33]

Does sound as if maybe the pump's giving out the wrong pressure readings, as it's happening on both steeds.

Another wee possibility, are you using correctly rated tubes rated for the tyres you're running?

Stu

 

[byegad]

Is it possible that the valve on your pump is giving you a lower number than what the pressure actually is?

That was my first reaction too. I've run tyres 14psi over maximum with no ill effect so stopping short by 10psi should have been ultra safe.

 

[DaveReading]

Pressure gauge on the pump misreading would certainly account for it, hadn't thought of that. My tubes have Schrader valves, so I can use the car pressure gauge to cross-check.

 

[byegad]

Pressure gauge on the pump misreading would certainly account for it, hadn't thought of that. My tubes have Schrader valves, so I can use the car pressure gauge to cross-check.

Good idea. Don't forget to tell us if that was the case, and by how much it was out, if in fact it was.

 

[Deleted member 20519]

If you've got a pressure gauge or a different pump to try out, go for it.

 

[Boon 51]

If you've got a pressure gauge or a different pump to try out, go for it.

Good call..

 

[Nebulous]

Check the tourer tyre. I got my tourer about 2 months ago, and the stock tyre came apart. Basically the carcase pulled right off the wire bead for about 3 inches. Edinburgh bike swopped it for another tyre from their display bike. They are very cheap tyres, and don't appear to me to match the spec on their website. Upgrading them is on my to-do list.

 

[DaveReading]

Thanks. I'll have a good look at it when I take it off tomorrow.

According to the spec, they are CST Traveller City Classic Road, Kevlar-lined and "proven for their puncture resistance" (!). I've read elsewhere that the downside is their weight and rolling resistance.

I don't anticipate doing more than 50 miles in one go over the next few months, and not heavily laden, so suggestions for nippier alternatives are welcome, or if there's a thread devoted to tyre selection perhaps someone could point me in the right direction ?

 

[Primal Scream]

This worries me as well, my tyres are supposed to run at 110 psi, up until last week I only had a normal pump without a guage, on Friday I purchased a Giant track pump, at 70 psi the tyres feel as solid as rocks and the resistance from the pump makes it hard to pump further. tbh I am wary of forcing more air in.

Is this normal?

In the dim and distant past all we ever did was pump up tyres until they could not be pressed in from the side.

 

[MattHB]

Being heavy I always ride on full rated pressure. Never had an issue.