Exploding Rear Tires?

Rick Huizinga

Active Member
Today I noticed that the rear tire on my new ST2 was splitting open near the rim:



The split developed after the delivery of the bike, which now has about 125 miles on it. The split varies in width and is about 4 inches long. If it develops much further, the worst area looks like it is ready to burst wide open.

It looks like other users have had their rear tire explode on them while riding. Translated from StromerForum.ch:

"Last Friday, has exploded in my rear tire or tube. In a turn (gyro), there was a very loud bang like a gunshot. Shortly after, I was on the ground and first did not know what was going on. The tube of the rear tire has soared, this meant that the tire flew off the rim and I crashed. I had contracted me luckily no serious injuries. This incident but could end badly in another driving situation at a higher speed. can I wonder how such a thing happen ??" Source: (Link Removed - No Longer Exists)

I just want to warn other riders to keep an eye on the rear tire in case this is a common problem. Having your rear tire explode while cornering could be quite a surprise!
 
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Ann M.

Well-Known Member
Interesting and problematic issue; have you contacted the dealer to update them on the condition? Maybe Stromer got a bad run of tires or they were overinflated when assembled or shipped to the dealer. Every rider should check their tire pressure regularly. Here in the Austin area where spring turns into summer overnight (that is, once it quits storming! :)) we run the tire pressure a few psi below the recommended top psi to allow for expansion due to heat off the road. Conversely, check for an underinflated tire; that generally shows up as a problem more often. With a heavier bike like the Stromer that's designed for challenging rides, the bead or other sections of the tire can be easily damaged going over potholes or off a curb with a large person or load with too little air. Low tire pressure could also allow the tire to roll too much and break the seal provided by the bead in hard cornering, thus causing a flat. So there are several things the rider can do proactively to keep the tires safe. Based on the image you loaded above, your first step really should be to contact the dealer and have them check the tire.
 

stevenast

Well-Known Member
Today I noticed that the rear tire on my new ST2 was splitting open near the rim:



The split developed after the delivery of the bike, which now has about 125 miles on it. The split varies in width and is about 4 inches long. If it develops much further, the worst area looks like it is ready to burst it wide open.

I did some searching, and it looks like other users have had their rear tire explode on them while riding. Translated from StromerForum.ch:

"Last Friday, has exploded in my rear tire or tube. In a turn (gyro), there was a very loud bang like a gunshot. Shortly after, I was on the ground and first did not know what was going on. The tube of the rear tire has soared, this meant that the tire flew off the rim and I crashed. I had contracted me luckily no serious injuries. This incident but could end badly in another driving situation at a higher speed. can I wonder how such a thing happen ??" Source: (Link Removed - No Longer Exists)

I just want to warn other riders to keep an eye on the rear tire in case this is a common problem. Having your rear tire explode while cornering could be quite a surprise!
Don't ride that bike until you get the tire replaced. Thanks for posting this!
 

Rick Huizinga

Active Member
Out of the box, the tire was inflated at 20psi. I've been running it at 45psi.

I'm not sure what caused the split, but when driving through the city, I've been running at power level 3 and accelerating quickly from stop lights so that I can stay in the regular traffic flow. The power delivered by the ST2 may be straining the tires causing a failure. One time, I took a corner a little too fast and ran over one of the raised yellow lane-divider bumps while cornering. This could have stressed the sidewall of the tire. In either case, the speed, weight & power of an electric bike could be placing alot of stress on the tires and we are seeing problems that may not normally develop on a normal road bike.

I've already ordered a replacement tire from Schwalbe. It turns out their distribution center is local, so I'll be getting a new tire tomorrow.

Stromer's website says that the tires are a custom Schwalbe BigBen 26x2.15", however the model number imprinted on the tire (HS439) is the same as the standard Big Ben from Schwalbe (http://www.schwalbetires.com/bike_tires/e-bikes). I'm hoping the only difference is the "+Stromer-" imprinted on the side-wall.
 
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MLB

Well-Known Member
That's likely a manufacturing defect. splitting at the seam like that, either a glue or sealing process that got compromised. (in all likelihood)

But you are certainly correct that the weights and speeds of E biking are a whole new set of demands on tires.

it's why I pray for the idio... guys out there going 40mph on bike tires and cheap framed bikes.....
 

Ravi Kempaiah

Well-Known Member
Out of the box, the tire was inflated at 20psi. I've been running it at 45psi.

I'm not sure what caused the split, but when driving through the city, I've been running at power level 3 and accelerating quickly from stop lights so that I can stay in the regular traffic flow. The power delivered by the ST2 may be straining the tires causing a failure. One time, I took a corner a little too fast and ran over one of the raised yellow lane-divider bumps while cornering. This could have stressed the sidewall of the tire. In either case, the speed, weight & power of an electric bike could be placing alot of stress on the tires and we are seeing problems that may not normally develop on a normal road bike.

I've already ordered a replacement tire from Schwalbe. It turns out their distribution center is local, so I'll be getting a new tire tomorrow.

Stromer's website says that the tires are a custom Schwalbe BigBen 26x2.15", however the model number imprinted on the tire (HS439) is the same as the standard Big Ben from Schwalbe (http://www.schwalbetires.com/bike_tires/e-bikes). I'm hoping the only difference is the "+Stromer-" imprinted on the side-wall.
I have had 4 flats on my ST2 and all of them were because of liners but I got rid of that problem. I also use a heavy duty tube and that has solved the problem.
Schwalbe developed a tire specifically for Stromer and it is also stated on Stromer's website. The difference is addition of 3mm "Green guard" compound that is used their "Marathon" models. Check this link: http://www.schwalbe.com

I have a feeling that the bead on your tire was not placed properly ! or may be it's just an accident.

Also, your dealer should be able to help you with the replacement.
I don't think normal Big Bens come with Greenguard compound. Let us know if that is not the case.
 

Rick Huizinga

Active Member
I got the replacement Big Ben tire today. It didn't have the GreenGuard puncture layer, like the Stromer version. It also has thinner sidewalls. It would be nice to know where we can get the Stromer version, preferably online.

After changing the rear tire, I performed a closer inspection of the front tire and it too is developing the same cracks near the rim, but not as severe. I'm going to watch to see if it gets any worse. If it does, I'm thinking of replacing the tires with the Marathon Plus (26x1.75) to get better puncture resistance. Changing the rear wheel is a pain on such a heavy bike, and I don't want to have to do it on the side of the road.
 

J.R.

Well-Known Member
Marathon or Marathon Plus would be a good solution. There are a lot of reasons a tire can delaminate, some are user fault, but it sure sounds like a defect. I hope you can pursue a warranty on your tires as these aren't cheap!

Was the replacement tire you purchased a folding version, or a wire bead tire?
 

Ravi Kempaiah

Well-Known Member
I got the replacement Big Ben tire today. It didn't have the GreenGuard puncture layer, like the Stromer version. It also has thinner sidewalls. It would be nice to know where we can get the Stromer version, preferably online.

After changing the rear tire, I performed a closer inspection of the front tire and it too is developing the same cracks near the rim, but not as severe. I'm going to watch to see if it gets any worse. If it does, I'm thinking of replacing the tires with the Marathon Plus (26x1.75) to get better puncture resistance. Changing the rear wheel is a pain on such a heavy bike, and I don't want to have to do it on the side of the road.
Schwalbe M+, especially 26x 1.75 is too narrow for ST2.
The bike comes with "Balloon tires" for a reason. Consider few options like Big Apple Plus (2.15"), Marathon Mondial (2.15") or Marathon Plus 26 x 2.0 (even though this is not ECR approved, it does well on speed pedelecs)

I think the dealer/Stromer owe you a replacement.
 

Rick Huizinga

Active Member
The Marathon Deluxe (26 x 2.0) appears to be an option as well. It is ECE-R75 rated and is considered to be a balloon tire too.

I'm working with Stromer for a replacement. Hopefully that works out, as I'd like to keep stock tires on the bike.
 
It was a wire bead tire, article number 11100557 from: http://www.schwalbetires.com/bike_tires/road_tires/big_ben
Today I noticed that the rear tire on my new ST2 was splitting open near the rim:



The split developed after the delivery of the bike, which now has about 125 miles on it. The split varies in width and is about 4 inches long. If it develops much further, the worst area looks like it is ready to burst wide open.

It looks like other users have had their rear tire explode on them while riding. Translated from StromerForum.ch:

"Last Friday, has exploded in my rear tire or tube. In a turn (gyro), there was a very loud bang like a gunshot. Shortly after, I was on the ground and first did not know what was going on. The tube of the rear tire has soared, this meant that the tire flew off the rim and I crashed. I had contracted me luckily no serious injuries. This incident but could end badly in another driving situation at a higher speed. can I wonder how such a thing happen ??" Source: (Link Removed - No Longer Exists)

I just want to warn other riders to keep an eye on the rear tire in case this is a common problem. Having your rear tire explode while cornering could be quite a surprise!
My rim needed to be re dished there was not a proper gap between frame and tire you should be able to hear the rubbing. You need to check gap with tire at rated psi. 1800 miles no flats yet. break sensor cable has failed, bad charger, 1.4 firm wear nightmare
 

Rick Huizinga

Active Member
My rim needed to be re dished there was not a proper gap between frame and tire you should be able to hear the rubbing. You need to check gap with tire at rated psi. 1800 miles no flats yet. break sensor cable has failed, bad charger, 1.4 firm wear nightmare
I hear some sound, and a slight resonating of the frame sometimes when walking the bike. Some are telling me its the motor, but I think its not rotating cleanly on the hub. The resonating comes and goes when spinning the rear wheel on a stand, but seems to always happen when walking the bike and turning left. Walking it straight, it comes and goes.

@Jed Charlesworth Can you explain more about the gap between the frame and the tire? I.e. where should I be looking?
 
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GW Shark

Member
I hear some sound, and a slight resonating of the frame sometimes when walking the bike. Some are telling me its the motor, but I think its not rotating cleanly on the hub. The resonating comes and goes when spinning the rear wheel on a stand, but seems to always happen when walking the bike and turning left. Walking it straight, it comes and goes.

@Jed Charlesworth Can you explain more about the gap between the frame and the tire? I.e. where should I be looking?
The tolerances of the city kit and the rear wheel on the ST2 are very marginal and I had the rear fender raised by my mechanic who leveraged a wrench against the rear wheel, coming up from the back and the fender to assist with clearance. This leverage was applied after the fender connections were loosened, and then retightened upon completion. This took care of the issue you described. To be certain, you could temporarily remove the fender, as I know Cory removed his permanently, and see if you still have the noise issue. Isolate and see if that is indeed the issue.
 
Can you see daylight between the tire and frame at the lower attachment of fender by botom bracket. My Bike has a much larger gap on drive (chain) side then on non drive side. My were mark was a little bit up 1/4 in from rim. This rubbing I am talking does not have anything to do with city kit or fender. It is the way the motor is laced into rim.
On warm days the rubbing was more noticeable because tire presure is higher. My Tires are branded with Stromer logo also. Good Luck.
 

Ann M.

Well-Known Member
If I understand you correctly, @Jed Charlesworth when you stand behind the bike and look at the position of the wheel/tire relative to the where the rear frame triangle starts, it is not centered? If so, your wheel was not dished properly and that does change the stresses on the wheel, not to mention that you could experience brake issues. You need to take the bike to the shop where you bought it for repair or wheel rebuild. Not a common problem, but this can cause spokes to break also and that would be hazardous.
 

GW Shark

Member
Can you see daylight between the tire and frame at the lower attachment of fender by botom bracket. My Bike has a much larger gap on drive (chain) side then on non drive side. My were mark was a little bit up 1/4 in from rim. This rubbing I am talking does not have anything to do with city kit or fender. It is the way the motor is laced into rim.
On warm days the rubbing was more noticeable because tire presure is higher. My Tires are branded with Stromer logo also. Good Luck.
Can you take a picture and post it? That would clarify the point.