blowout....

[ghouluk]

bit of a weird one this, but i had a blow out a couple of days ago, quite severe (the guy whose truck i almost ended up under said he thought someone had shot out my tyres) changed the tube (which was destroyed completely) and pumped up the new tube which promptly exploded again.

rechecked the tyre and rim, but no marks,so inflated the next tube slowly and noticed the bead was not seating properly and pushing off the rim (which ruptured the tube as it popped out the side, pumped a bit, reseated, pumped a bit, reseated and got it up to the 80psi no probs.

I did around 30 miles on it yesterday without a problem, but the ride seems very harsh, and the tyre isn't running true (the wheel is fine) I'm guessing that the blowout has ruptured the bead somehow (tyres are schwalbe big apples) and i should really replace the tyre, but any other thoughts?

on the plus side, thats the last of the cr!ppy original tubes gone

 

[RobF]

I'm not surprised the ride is harsh.

Generally, the bigger the volume of air in the tyre, the lower the pressure.

You are running 80psi which is a lot for a near-balloon tyre.

Most mountain bike type tyres run at between 40 and 60psi.

Also, the sidewalls on the bigger volume tyres don't like excessive pressure which could explain the problems you've had.

The pressure range should be marked on the side of your Big Apple - I would run in the middle of the range or towards the lower end.

 

[Zebb]

Yep I run max at 60psi, side-walls would just give way much more.

 

[Wander]

The Schwalbe Big Apple tires have a very wide range of permitted air pressures. You can go as low as 30 psi with such a tremendous volume of air in the tires, on the other hand the upper limit is 70 psi.

Schwalbe Big Apple

Aslo some have maximum 55 psi:-
Big Apple HS 430 | Schwalbe North America

 

[ghouluk]

Guys, thanks for all the opinion and advice, and the problem is solved, but just to clarify - i've always run my tyres at higher psi, even when i was riding serious downhill, i never went below 50, its personal choice and as i'm a fat git i prefer my tyres harder. I've run the big apples at 70-80psi for the last 2000 miles without any problems, sorry should have made that clear.

If i run my ran my tyres at 40psi with my 100kilos on it, id be riding on the rims, I ride where the ride is good for me, and the battery range is maximised - for my weight on the big apples on the bh xtreme, that 70-80psi...however.....the pressure gauge on my track pump is reading a little out i'd say, i put the mini pump on it, to check and when the track pump reads 80psi, the mini reckons 120psi - ooops.....but i guess that explains the blow out

it does give you an idea of how far you can abuse your tubes and tyres though - yes i blew two of them, but yesterday i did 30 miles on 120 psi (probably more as thats what it was reading this afternoon when i looked at it)

 

[Scimitar]

I run my Fat Frank rear at 40psi and that's with me (105kg), bike, battery, motor, shopping, other crap, etc, on it. Anything approaching 30psi and I can feel it start to squirm on cornering, but 40 is just nice for comfort.
Actually, it's really handy to know that I could sorely abuse the rim much more than I've been doing, so there's a fair bit of leeway in it. I came across a tale of woe, where an owner had sprung the walls of his rim by over-inflating a balloon tyre.

 

[Yamdude]

I like the tyres on my hybrid pumped up to the max, they just roll better.
The Kenda 700x45 that have been on my hybrid for the last 7 months, are rated 85psi max, and I run em at 90psi. Never had a puncture.

 

[eHomer]

I can throw a similar experience into this thread, and it was a first blowout for me too.

I had brand new Schwalbe Marathon Plus 26 x 42 fitted to my Dutch Spartamet motorised bike (a petrol 30cc engine in the back wheel )

This Summer I rode it about 3 miles to a nice quiet Marina, put it on the centre stand and walked over to a boat. There was than a really loud bang (just like the OP's tyres being "shot out"), which grabbed everyone's attention for 100 yards around me.

I thought, being petrol, the bike must have exploded or something, but no, it was the rear tyre, hanging off the rim. It had done exactly the same, the bead had popped off while at 60 psi and the tube had exploded and shredded with a 6" long slit.

It was a real bu**er to fix, because the engine is in the back wheel, so to change the tube the whole lot had to come out.

I rode home OK, but the next day it popped off the rim again, but this time the tube didn't explode, so I was able to ease it back in and ride home slowly.

The tyres are the less common 26" with the 590 rim, rather than the much more usual 559, because the engine wheel is a special alloy casting with webbed alloy spokes.

I'm 100kg in weight as well (twice the man I used to be), so I guess the stress is increased, though I've never had it happen with any other bike or tyre in 50 years.

Here's the strange thing though, I then swapped the tyres over, front to back, (both the same Marathon +). I've since done about 500 miles, with no further problems.

Conclusions - Either the tyre was faulty, or I had strained it when first putting it on the shallow cast rim. It was much more difficult than fitting onto the normal deeper section front wheel. I assume it's been ok on the front either because that's a conventional wheel, or it's much more lightly loaded, or both...

 

[oigoi]

I have noticed on several occasions when changing bike tyres on mountain bikes in recent times that the fit between the tyre and the rim was quite loose, I'm not sure if tis is as a result of the tyres being made slightly too big and loose or the rim being on the small side. One bike I did (a cheapo tescos moutain bike with it's original tyres on) it was clear that if I inflated the tyre too hard (much more than 40psi) it was goig to be pushed off the rim.
I suspect in some examples it is down to chinese low budget manufacturing

 

[Yamdude]

Doh.... wrong thread.

 

[Scimitar]

I have noticed on several occasions when changing bike tyres on mountain bikes in recent times that the fit between the tyre and the rim was quite loose, I'm not sure if tis is as a result of the tyres being made slightly too big and loose or the rim being on the small side. One bike I did (a cheapo tescos moutain bike with it's original tyres on) it was clear that if I inflated the tyre too hard (much more than 40psi) it was goig to be pushed off the rim.
I suspect in some examples it is down to chinese low budget manufacturing

I wonder if the Chinese 26" spec is slightly different to ours. Could cause some looseness of fit.

 

[oigoi]

I wonder if the Chinese 26" spec is slightly different to ours. Could cause some looseness of fit.

I could see how some confusion could easily creep in and cause a mismatch. i remember reading Sheldon Brown's page on all the different bike tyre sizes used in the UK, Europe and the US and thinking how overcomplicated the situation was. Be much better if there was some kind of international standard everyone was working to

 

[mike killay]

Sorry to resurrect an old thread but this has happened to me recently. Basically, I have run for years on Kenda, then Schwalbe road cruisers without problem.
But I have fitted Marathon Pluses to both wheels, on the rear rim, the tyre will simply not connect the wire bead to the rim shelf and constantly blows out.
It seems that the tyre is too big, but it is exactly the same as the front one that has no problems.
I seem to remember CWAH or someone complaining recently of a similar problem.

 

[soundwave]

i had to change my front tyre on my bike the other day and had to blast 65psi in to it to get it in to the rim with stans no tubes in to seal it up. no chance with a foot pump.

was a right pita to get it on as well tho better than the 30 quid to have it fitted.

 

[mike killay]

what is 'stans no tubes'?

 

[soundwave]

http://www.chainreactioncycles.com/stans-no-tubes-the-solution-tyre-sealant-2015/rp-prod38850?gs=1&gclid=CLjt6KXC28UCFerpwgodVq8AZA&gclsrc=aw.ds

seals the tyre beads for no tube tyres will leak other wise

 

[Deleted member 4366]

I had it too recently with MPs. I think it's when the wire gets stretched by not fitting it correctly when people try and lever the tyre over the rim without getting the rest of the tyre in the well. Once stretched, the tyre will never fit. It just blows off when you pump it up.

 

[mike killay]

The culprit

Because I needed a new tyre today, I went to Halfords, the only ones they had were schwalbe Silento which look similar to MP.
I told the mechanic of my problem, not having yet discovered the true cause. He told me that he had never seen a stretched wire.
He then went on to say that 'Specialised' rims often do not accept standard tyres.
Interesting.
I guess my faulty tyre must be a factory escapee

 

[steve.c]

Hi All.A lot of you may have seen my rim when I kept gettind punctures ive put it in here again but on another instance I had replied to a tyre question saying that I had bought 2x mountain bike tyres for 14 odd quid and had no problems then on my way home the next night dark-wet-cold and doing about 25mph the back tyre went BANG and the split in the tyre and tube was about 4" long so had to push !!!! SO DONT BUY CHEAP TYRES !!! and went back to Kendas and no probs since (wait till tomorrow ???) I run the front at about 45/50psi and the rear at about 55/60psi with no probs but my lightwait Marin is much more comfortable to ride.
Regards SteveView attachment 11389View attachment 11389