I am 6'6'' and 330lbs and have concerns about the stress on the wheels with ANY load. I can see that from some of the tire pressure calculators on the net that I should set the tire pressure to ~152lbs (37mm tire). According to my tires the max pressure is 85lbs (New Surly Disc Trucker with factory continental contact tires) so is there a touring tire that can handle the extra pressure that I need? Should I increase the tire size and if so what tire size and model should I go to?

I tried searching the forums/net and I have not been able to find info on what to do.....I am sure there are big guys on a tour who have run into the same issue.

I think 85 should be fine. I at one point weighed 275, and rode with about a 60 pound loadish. I never noticed anything. I ride 35mm, and normally I go with really light tires for lower rolling resistance, so they sorta look like 1.25s if one was comparing apparent bulk. On one trip I got into a sandy section for about 40 miles where I dropped the tire pressure for more floatation. I thought I had dropped it a reasonable amount, and it worked great. I did pay attention when approaching hard edges like bridges. When I went to pump them up, the built in gage showed something ridiculously low, like maybe 20 pounds. No pinch flats. But at that pressure, I was lucky, and careful. I think some of it comes down to taking care with the bike, some folks jump off curbs etc... I am always looking for a smooth ride.

Your weight shouldn't destroy a wheel, dynamics are far more important. At the time I was riding Alex downhill rims, straight spokes, and LX hubs. I even crashed into a big rock on a trail, and it broke the tire cassing, but did not harm the wheel.

There is also a Clyde forum here you could ask on, but the reality is that your issue isn't a problem, there are tons of tandems etc... They are running on pretty standard set-ups.

Sheldon Brown once posted a formula for tire pressures that factored in weight, tire size etc, that (at least for me) seems to strike a good balance between tire wear, comfort, control and efficiency. Sorry I don't have the link handy but it should be searchable.

Sam

I think I found the link....good info!
https://sheldonbrown.com/tires.html

this is probably a good tire:

https://www.schwalbetires.com/bike_ti..._dureme_tandem

my pressure table gets up around what you need:

https://interdependentscience.blogspo...-pressure.html

I would think the Schwalbe Marathon and its siblings would be an excellent tire since they have such a tough heavy sidewall that would withstand the load better than a light weight tire designed for speed. But I agree, the Clyde forums have probably been thru this topic countless times.

the Berto Tire Pressure app for android says 87 rear and 72 front for that tire width and your weight

I weigh 400 lbs and I've run Schwalbe 40mm Duremes at 60 psi and never got a pinch flat. My normal pressure for these tires is 70 psi (with 80 being max recommended).

Lurch, consider putting on a larger rear tire like a 40mm schwalbe Dureme or Mondial. The rear tire wears away 3x faster so that's the one to pick first.

i'm betting you misread the calculator/chart just like I did the first time I looked at it... the weight curve is based on per wheel... so if you are 330# (not far off from what I am btw) you will want to take about 1/2 that... my guess is prob 70-80psi would be about right...

take a look at the 2nd calculator on this page... if you use the first one that is weight at the wheel, if you run most of your pannier load up front you'd need more pressure up front, load out back and more pressure in the back.
https://www.dorkypantsr.us/bike-tire-...alculator.html

Psimet on the road forum posted a good formula....

https://www.bikeforums.net/archive/in.../t-410701.html

From an engineering point of view, if you were to try 150 psig in a 37mm tire and did not split the tire, you could risk damage to the rim. Some rims are rated for max pressure for different tires sizes. My 37mm tires are rated for 87 psig, my 700c tiouring bike rims are rated for 88 psig with 37mm and 103 psig with 28mm tires.

As far as a split for 70 ish front, keep in mind that in one world the idea is to put more weight in the forward panniers. So you may be a little more balanced than a chart would suggest.

I think another way of looking at this is not so much from the will it break perspective, tires are pretty tough, but from the what do you want it to do for you. At 6'6", I'm guessing that is a reasonably fit weight. A lot of hefties want a comfort ride, however. I'm slightly hefty, and also a little arthritic. So I want a comfortable ride, but part of that is efficient. So all these factors are tunable. You get on the bike and you work it out. If you want small light slick tires for low rolling resistance, and also wanted a little compliance, then no crashing into curbs for you. Maybe you need to carry a spare. If you want to blow through rough trails on your tours, then maybe you need to move up a size, keeping in mind the performance trend towards larger wheels and tires these days. Maybe still slicks for rolling resistance.

At that weight, I would be giving considerable thought to the wheel build. Your are in tandem territory, and there are industry standard specs for wheels and brakes at that performance level.

Also, it is always easy to take a recommendation for some fat, thick, tire. but if you never try the lighter end of things, you will never know how it would have worked out.

My wife and I tandem. Our all-up weight is about 350 lbs. We run 25mm tires like Conti 4000s or Schwalbe Durano at 120 psi very satisfactorily. We run 28mm tires like Michelin PRO4 Endurance (sold as 25mm) or Vittoria Rubino Pro Tech at 110 lbs. We don't ride much on gravel and find no need for wider tires. We run 36H Velocity Deep-V rims with no problems.

Edit: I forgot to mention that when we tour, our all up weight is 400 lbs. and we tour on the Pro Tech 28mm tires at 115 lbs. We like the PRO4 Endurance tires so much, though, that next tour we might be on those.

The PSI in the tire is only one part of the story. The other part is how stiff (or not) the tire casing is. What you really need to do is (with help of a friend) measure tire DROP when you sit on the bike in the same position you ride.

So you measure from each axle to the ground unloaded, then get on and measure again. The difference between these two measurements is how much the bike dropped from the tires being squished. Next, measure the HEIGHT of the tire from the rim to the outer edge, do NOT use the width, and especially do NOT use the listed width on the side of the tire.

Let's say you're riding 700c x35mm tires with a rim edge to outer edge height of 37mm, and when you sit on the bike it drops by 5mm, that would be about 13.5% drop, which is just about perfect. Any less and you're riding an unnecessarily hard tire and would be better off letting a bit of air out, any more and you run the risk of pinch-flats and rolling resistance increases for no good reason.

Now let's say you get on the bike and measure 12mm of drop, that'd be 32.4% drop, which is much more than needed for an optimum ride. In this case you should inflate the tires more until about 15% drop is attained (different tires ride better/faster at different drop, so this is a rough, but fairly accurate figure).

If your tires are already at maximum pressure and your tire drop is still very much more than 15%, get wider tires, they have less drop at any given PSI and handle load better. For instance, 50mm wide tires would be easily inflatable to 50-65 PSI depending on model, and at that pressure, even at your weight they'd have very little drop, probably about 10% or less.

.

I'm not super knowledgeable on this subject, but I'll share what I run. I'm 280 pounds, and tour with some gear that isn't lightweight, on heavy steel framed bikes. This year we just got out for a couple of short bed and breakfast tours, but in the past I've gone on a few short cycle camping trips where my bike was quite heavy loaded with all my camping gear. Since I was solo touring I had everything for camping on my bike, I always fail at packing light and bring anything I think I might need and spares for everything, and I have yet to replace some of my camping gear with light-weight stuff suited for cycle-camping or hiking. Long story short, I put a LOT of weight on my tires!

I use 26" wheeled bikes, but both the tires I run also come in 700C sizes. On my tourer I run Vittoria Randonneur Pros (26 x 1.5") front and rear. For my commuter, that I used for the B&B tours this year, I run a Rando Pro on the rear and a Panaracer T-Serv Pro-Tex up front. The Panaracer is nominally a 1.5 inch tire as well, but I purchased the 1.75" size knowing that they run small. I run it at the upper listed pressure for the 1.5" T-Serv, at 75 PSI. The Rando Pros I also run at the upper limit of their listed pressure at 90 PSI. Being as heavy as I am, and even when I'm commuting I'm usually carrying a load (heavy schoolbooks or lunch and workclothes), I seem to get a lot of sidewall deflection if my tires aren't pumped up pretty high. The Vittoria's seem especially good in this regard, and that's why I've got one on the rear of my commuter. The Panaracer doesn't have as stiff a sidewall as the Randos, but the higher rubber content makes it a little cushy for a front tire. Both of these tires have excellent puncture resistance.

I've successfully ridden both tires over all sizes of gravel and on bare dirt, loaded.

I wouldn't go too much higher than the recommended pressure for tires. Not only are they going to be overly stiff, but the manufacturers usually put a lot of research into the recommended pressures for their tires.

Hope that helps!

+1

I'm still learning about wheels, but I think something needs to give somewhere, and so you want your tires not rock-hard when you weigh as much as we do, otherwise I think you'll find that you are going to be snapping spokes and/or having the rim fail one way or another.

Great info! After reading this info and searching the net I think I should increase my tire width to 40mm tires. I think the Schwalbe marathon dureme tires are the way to go just dont want a tread pattern that is too aggressive for 80% road and 20% light off road (compressed dirt road).

In July 2012, I did about 500 miles around Glacier National Park on 40mm wide Schwalbe Marathon (with Greenguard) tires, not the Duremes. Listed as 26X1.5. They worked great.

These are really durable tires, I ride the 42-622 on my Hunq and am surprised at how fast they roll. You might also look at the Schwalbe Big Ben.

Marc

This. The wider the tire, the more it stresses the rim at a given pressure. For example, MAVIC A719's are rated to (I think) 75psi for a 32mm tire. 150psi with a 37mm tire is going to greatly exceed the rating of most any rim.