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Old 03-14-13, 07:18 AM   #1
wheelinthai
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What is the maximum load for 700C X25 tyre?

I've been thinking of using lighter tyre for touring, such as Continental Gatorskin (700c) 25c. I'd like to know if I'll be limited by load capacity for such small tyre. How many pounds load including the cyclist can you expect to use this tyre safely?
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Old 03-14-13, 08:27 AM   #2
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I toured across the US last summer on a 25 mm tire, a heavy Schwalbe. I rotated them once and I'm still riding them, over 10,000 km on them now (one puncture so far). (Good value for the money, but too heavy for total enjoyment. Next tire will be the Gatorskin--I heard good things about them.) I had a packed load of about 10 kg added to my 70 kg body mass, a pretty light load overall.

I think a bigger factor than static load on the tires is the dynamic load you subject them to on the road. And the handling, of course. The tires have to be built for the impact of a pot-hole or a curb, and for sustained rough handling on a gravel or dirt road. I don't think you can put a simple weight capacity number on a tire, given all those variables. I rode enough gravel and dirt paths to know that I pushed the limit on the 25 mm tires. But they sure were nice on the other 99% of the tour.
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Old 03-14-13, 08:51 AM   #3
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...How many pounds load including the cyclist can you expect to use this tyre safely?
You should ask Continental for load rating.
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Old 03-14-13, 08:54 AM   #4
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Not sure about loading, but I would think you may get more flats with a thinner tire at a higher pressure. Then again, "more flats" may still mean no flats if you're multiplying 0 times whatever. : P
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Old 03-14-13, 09:01 AM   #5
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Originally Posted by wheelinthai View Post
...load capacity ... including the cyclist...
This is such and important issue for all the bike parts and components - Unfortunately I have not been able to find decent answers - Every thing gets squirely at about 250# and most load tables for bike frames only go to 100 Kg (220#) - Yet I routinely see riders out there mashing away at greater than 280# (and more power to them!!!)...

(At 240# I personally am holding back on ridding a PX-10 SLX for fear of wrinkling it...)

Last edited by zandoval; 03-14-13 at 09:07 AM.
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Old 03-14-13, 09:47 AM   #6
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Definitely will have to keep your tire pressures near the max. as snake bite flats are more prone with heavier loads and smaller tires. The ride isn't as compliant nor as forgiving, and for those reasons, I quit touring on tires of that size and now won't go below a 28 and generally lean towards 32's unless I know all the roads I'll be riding on are in fine condition with little gravel (which is rare)
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Old 03-14-13, 10:20 AM   #7
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28c or wider tires can handle more load at lower pressure. This reduces stress on the wheels and rider. The contact patch is also rounder for greater stability in all direction. You can always decrease rolling friction by adding more pressure, but too much pressure will cause the bike to hop on rough roads, which would decrease traction and speed. A little extra tire weight will only require an additional 2 watt (1%) to maintain 18 mph cruising speed. Most of the work output is to fight air resistance.

All else being equal, there is no real-world advantage in touring with 25c or smaller tire. Remember that at any given weight, the total contact patch area between the tire and road is the same with 25c and 28c.
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Old 03-14-13, 11:57 AM   #8
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We run 700 X 25c on our tandem with no issues. All up weight around 350 lbs. So, like, no worries.
We like:
Michelin PRO4 Endurance
Conti 4000s
Schwalbe Durano

These tires are all very good rollers, hold well in the wet, and are fairly flat-resistant.
Inflate enough so that you don't get pinch flats.
For our loading, I inflate to 120 psi. Most tourers would use quite a bit less.
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Old 03-14-13, 02:18 PM   #9
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If you have to load them heavily, Bring More Spare Tires. ... at least a 3rd.
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Old 03-14-13, 03:54 PM   #10
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If you have to load them heavily, Bring More Spare Tires. ... at least a 3rd.
We think carrying a spare tire is a great idea. We happen to carry a 225g 23c Vredestein Tricomp. In many thousands of miles of tandeming we have loaned it out a few times, but never needed it ourselves. Michelin claims that our current PRO4 Endurance tires, the best we've ever run, are also 225g. 225 * 3 = 675g. All three of our tires thus weigh less than a single tire which one often sees recommended here. The tubes are lighter and smaller, too. Weight saving cascades.

25c at our weight is narrow for gravel. We tour at 400 lbs. on 28c. While we have ridden many kilometers of gravel and cobblestones on 28c, such narrow tires at that weight are not the best choice. But for pavement, they work great. Giving a little more margin for touring, anyone with an all-up weight of 300 lbs. or less can tour just fine on 25c. At that weight, wheels will be a bigger issue than tires.
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Old 03-14-13, 04:35 PM   #11
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general rule of thumb - if you're using lighter tires, carry lighter loads.

I'm hopefully going to tour this summer on 29er tires, also 35s, and 28s on a road bike.

With the 28c tires will aim to carry about 15 pounds of gear, max, plus 180 pounds of rider.
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Old 03-15-13, 09:22 AM   #12
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Some people consider a 15 percent tire drop to be ideal. I however consider it to be my minimum pressure and I usually run higher pressures. But, I do not run pressures higher than my tire rating.
http://www.bikequarterly.com/images/TireDrop.pdf

Look at the graph on the last page at this link. Note the line for 25mm tires. Use your tire max pressure rating to find max load on the tire for the 15 percent drop. Example, if your tire was rated for 130 psig (y axis), then your max load on that tire would be found at 143 pounds (on x axis).

You certainly could put more load on the tire, but you would be more likely to get pinch flats or damage something when you hit a big bump.

I have printed that graph and used a ruler to draw lines further to the right to estimate pressure that I want for the higher weights that I run on my rear tire when loaded. I use about 87 psig in my rear 37mm wide touring tires.
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Old 03-15-13, 11:58 AM   #13
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Originally Posted by wheelinthai View Post
How many pounds load including the cyclist can you expect to use this tyre safely?

Schwalbe USA lists load capacity for their tires and that should give you ball park numbers for most quality tires. Their 25mm Durano, which I use for supported event rides, is listed at 70 kg.
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Old 03-15-13, 12:19 PM   #14
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I used to run 27 x 7/8 many many years ago......until I got old and feeble.Then I carried 2/3 times as much weight as I do now.Never really had any major problems,just the normal flats that come with thin tires.
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Old 03-15-13, 05:16 PM   #15
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Touring tandems always push the limit of what is possible with the available combinations of rims and tires, which are almost universally developed for single bike use. So we know where the limits of usability and safety lie. There is a very simple formula to calculate acceptable pressures for a touring tandem: (nominal tire width in mm)*(tire pressure in psi) = (between 3000 and 3200). For instance, 25c * 120 = 3000. It happens, and not by chance, that the maximum sidewall pressure on suitable quality tires follows this formula. You can look it up max pressures on any manufacturer website. This formula also follows the recommended maximum inflation pressures for various tire widths as published by various rim manufacturers.

This formula also works. If you are touring with a tandem and inflate following this formula, it is unlike that you will have pinch flats unless the tandem team is unusually heavy. We have proven this by touring with tires that follow this formula and never having a pinch flat. These pressures are not necessarily optimum for the use. However, tires and rims offering higher pressures do not exist.

One can extrapolate from this formula to produce a formula for a tire pressure, that will not normally pinch flat, for any loading as follows: (tire pressure in psi) = ((weight of bike, load, and rider) * 8)/(tire width in mm). For example, take a bike, rider, and load weighing 200 lbs, and running 25c tires. 200*8/25 = 64 psi. I realize that seems very low, much lower than anyone would normally consider. Did I mention that the tire and rim choices for tandems are not optimal? However, it is what it is. Racers at last year's Paris-Roubaix ran tire pressures around 60 psi on 27c tires, so this figure is not absolutely crazy.

Of course most folks would pump higher than the absolute minimum.
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Old 03-17-13, 07:17 AM   #16
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run 25 mm conti gp 4 season tires on my gunnar roadie, conti suggests a min inflation of 95 psi, i run them at 90 psi.
my mASS including bike and pack run around 120 kg - have not had any tire related issues (5000 km). more concerned about wheel integrity.
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Old 03-17-13, 07:45 AM   #17
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...my mASS including bike and pack run around 120 kg...
Coffee just came out my nose.
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Old 03-18-13, 02:34 AM   #18
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I toured across the US last summer on a 25 mm tire, a heavy Schwalbe. I rotated them once and I'm still riding them, over 10,000 km on them now (one puncture so far). (Good value for the money, but too heavy for total enjoyment. Next tire will be the Gatorskin--I heard good things about them.) I had a packed load of about 10 kg added to my 70 kg body mass, a pretty light load overall.

I rode enough gravel and dirt paths to know that I pushed the limit on the 25 mm tires. But they sure were nice on the other 99% of the tour.
Thanks for your hands on experience. Very helpful, particularly you're exactly my weight. I don't intend to ride gravel or dirt road. I like to zoom on light agile bike, especially dicing with my friends. Most my tours are sagged, sort of, with hotel and no cooking.
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Old 03-18-13, 02:38 AM   #19
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Also thanks for all you guys who helped with information.
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