Heavy duty tubes; they sound like just what the doctor ordered for dual sport adventure riders. Hey, they are heavy duty – that must mean they are a better choice than normal tubes, more puncture resistant, and longer lasting. But is that really the case? Let’s talk about it.
The desert is a harsh mistress
Several years ago six of us went on a three day expedition into the desert of northeast Mexico. Our group included 4 dual sport bikes with tubed tires and 2 adventure bikes with tubeless tires. Notably, all 4 dual sport bikes had 21 inch front tires and 17 inch rear tires. That’s an important point to take note of.
About 6 hours into day one we had the first flat of the trip. One of the KLR riders got a big ‘ol thorn in his rear tire. Luckily the rider had a spare rear tube and a short time later he had the tire repaired and we were back on our way. This is a picture I took of him as he was working on the bike.
It didn’t take all six of us to fix the flat so Uncle decided a little rest was in order. It being the desert, there weren’t any shade trees, so he did the next best thing and laid down in the tiny spot of shade provided by his motorcycle. In the words of Clint Eastwood, he adapted and overcame.
That flat was the only bike issue we had on day 1. Sweet!
But early on day 2 we got the second flat of the trip, . As luck would have it, this was also a rear flat on a KLR, caused by a thorn.
This is where the problem started. Two things came together at this point that derailed the remainder of our trip.
1. No one had a spare rear tube.
2. The tube with the thorn in it was a heavy duty tube.
At this point you might be saying to yourself, “No problem. Just use one of your spare front tubes you guys are carrying.” While it is true that each of us were carrying spare tubes, they were all 21″ front tubes. The only spare rear tube that anyone brought had been used the day before. I know you’ve heard that in an emergency that you can use a front tube in a rear tire. That will work on a dirt bike with a 21″ front tire and a 19″ back tire. However, it won’t work when you have a 21″ front tire and a 17″ back tire (a common combination on 650 dual sport bikes). The 21″ front tube will quickly rupture if run in a 17″ back tire. I learned this fact the hard way a few years previous to this trip when I attempted to run a front tube in the back tire of my KLR. I had been told the same thing – “no need to carry two tubes, just run the front tube in the rear tire until you get back to civilization”. That is bad advice for KLR riders (or anyone with a 21/17 combo). The tube ruptured about a mile after I put it in. I was was riding 70 mph on the highway in heavy traffic at the time it happened and the sudden deflation of the back tire made things very interesting.
“No problem,” you might be thinking, “just patch the tube and get back on your way”. This is where problem #2 rears its ugly head. You can’t patch a heavy duty tube. At least not with a normal patch kit. The patch won’t stick, no matter how much glue you put on it. I’m not sure why – I’ve been told that heavy duty tubes have more silica than normal thickness tubes and that’s why patches have difficulty sticking. Whatever the reason, patching the tube is not an option. The reason I was running a 21″ tube in a 17″ rear tire in my story above was because I had a heavy duty rear tube on the KLR. When I got that flat I attempted to patch it but couldn’t get the patch to stick. So, I finally decided to put in the front tube, with nearly disastrous results.
At this point, we didn’t really have much choice. Patching the tub was our only viable option. The tire was pulled off, a patch applied, tire reinflated and remounted. And off we went.
Within about 1/4 mile the tire was flat again. So the process was repeated again. Remove the tire, apply a new patch, reinstall, reinflate, and take off again. Within a few hundred yards the tire was flat again.
Over about a 3 hour period we patched that tube 3 times. There was a lot of standing around as the tire repairs were underway.
The third time the tube went flat the valve stem tore away from the tube, making the tube completely unusable. In desperation we installed one of the front tubes but in a mile or two that tube ruptured.
Out of options, two of us rode to the nearest town and enlisted the help of one of the locals with a pickup to fetch our friend out of the desert. The local also called around to various stores and mechanics in the village and was finally able to locate a single, ancient, 18′ inch tube in a small hardware store. We bought it, installed it the next morning, and the tube held on the 200 mile ride back to the Texas border.
The fact that you can’t patch a heavy duty tube might not be sufficient to persuade you not to run them on your dual sport motorcycle. After all, they are heavy duty, they must be more puncture resistant. And you can always carry a spare of the right size.
Are they really more puncture resistant? No, they aren’t. Think about it this way – anything strong enough to puncture the incredibly thick, dense rubber of your tire isn’t going to stopped by a tube, no matter whether its heavy duty or not. If it punctures your tire, it’s going to easily puncture your tube too.
So what is the advantage of a heavy duty tube? Why do they exist? The one major advantage of a heavy duty tube is that it is more pinch-flat resistant than a normal tube. Which makes them a good choice for dirt bikes ridden in rocky terrain. Dirt bikes run very low tire pressures (10 – 12 lbs), which makes pinch flats a common occurrence. Heavy duty tubes help prevent pinch-flats. That’s it, that is their main benefit.
Dual sport motorcycles don’t typically run such low tire pressures because they don’t have rim locks. Without a rim lock you need to run a minimum of about 18lbs pressure in order to prevent the tire from slipping on the rim. Higher tire pressures make the tire much more resistant to pinch flats, negating the need for a heavy duty tube.
1. Heavy duty tubes might seem like a good choice for the dual sport adventure rider but they aren’t. They don’t offer any real benefits for the dual sport rider but they do have some real disadvantages, the most serious one being they are extremely difficult to patch with a normal patch kit.
2. You can’t run a 21″ tube in a 17″ rear tire so carry both front and rear spare tubes.