Am I too heavy for my road bike tires?

I raced 5 Ironman races (so 112 Mile / 180 Km) bike segments and did training for that for 5 years. I raced at 235 lbs and now I am riding 30 miles to work at 270 lbs (alas!) and I do not have an issue with pinch flats.

My road tires I run at 120 lbs or so of pressure. Though with the recent hot weather my pump was not getting the pressure that high due to over heating.

So I would say, no to your question.

I'm just a tiny bit smaller than you (~10 pounds lighter, depending on what I've eaten that week) and have ridden 700x25 tires/32 spoke rims with no problem. Granted, I keep my tire pressure high, and go over curbs like I'm carrying a baby inside a priceless ming vase, but still.

You didn't tell us at what pressure did you inflate your tires and that's a important thing when it comes to pinching the tire.

Road bike tires can be easily inflated up to 7-8 bars (100-115 psi) and for your weight, I think this would be enough to protect your tire.

I ride a trekking bike and inflate the tires to 4.5 bars (65psi), similar weight as you and I don't have problems with pinched tires. Granted, the tire dimension is bigger, but the pressure is also half of what the road tire would have.

My girlfriend and I inflate the tires on our touring tandem to 90 psi. The bike carries both of us plus two fully loaded panniers in the back. At 90 psi in the tire with what probably ends up being over 350 lbs on the bike, we have never had a pinch flat. That said, I drive the bike very carefully to avoid hitting anything with a sharp edge (lots of driveways have a nasty edge on them). I wouldn't recommend over-inflating your tires (they're rated for a reason), but if you're getting a lot of pinch flats, you might consider riding a little more conservatively. A little caution can go a long way toward making things last.

You are under inflating your tires. I am 6'8", 270 lbs and ride successfully on 23x700 at 120 lbs pressure. I had pinch flat problems with 23x700 on my tandem which were resolved by using 25x700.

I terms of the "am I too heavy for my tires?" question, you can look for the specs on the tire maker's site. Schwalbe publishes a rated load for their tires, I'd expect that other reputable makers do as well.

As a point of reference their Marathon Plus tire is rated for a load of up to 90 kg / 198 pounds in a 32-622 size (probably at 6.55 bar / 95 psi). Since there are two tires, you'd be good for 180 kg (almost 400 pounds) with a pair of those tires.

I had this same question so I did some looking around.

Here's what I picked up --

The simple formula for figuring out which tire works for you. Take the amount of contact area of the tire on the ground and multiply by PSI you have in your tire.

So, the "area" (width times length) of the tire along the ground, multiplied by the psi.

So, 2" of tire down contacting the ground (when you're sitting on it), by 1" wide tires. 2 x 1 = 2 square inches. If your tire is pumped to 100 psi, your maximum weight for that tire would be 2 x 100 = 200 lbs. That's both your bike, the rider, and anything you are carrying. (try to get an idea of whether the area down is appropriate)

Also be aware that the weight is distributed between both tires. So technically, this bike's tires should be capable of 400 lbs if you have 2 tires with the same attributes and psi.

You probably should over-specify the weight carried. I would probably spec 25% extra at least.

So, rearranging the formula with algebra.

Area x psi = weight

area = weight / psi (weight divided by psi)

So .. if you and your bike and whatever was loaded on the tire of the bike were 200 lbs... if your psi were 50

area = 200 / 50 = 4 sq inches

You'd probably not want the length of the tire's area on the ground to be very long.. so you'd want a fairly wide tire, say 2 or 2.5 inches wide (that's pretty wide..)

4 / 2 = 2 inches for the length. (2x2 sounds light to me)

Remember that's double capacity. 400 for the whole load on the tires.

So 300 lbs of man + bike + carried supplies with a 33% over spec. (1.33 x 300 = 400)

Other considerations --

The wheels need more spokes. The info I'm giving is by inference from someone stating that a "tandem bike" (with 2 or more riders) that had a 500lb load would have "more spokes in the wheels".

Common spoke counts are around 28, 32 or 36 for "normal" applications, and for a tandem wheel it's in the 40-48 spoke range. So more spokes for more weight. There are also wheels that are "mags". Rather than spokes, they have 3 or more solid pilars from the hub to the rim. If you're really concerned about weight / strength / durability, they might be a consideration.

Then, there's the question of tire width, and whether your wheel can hold the tire width you want.

And finally, whether the wheel is an appropriate size to fit on your bike.

There are of course other considerations -- quality / metal compositions / psi ranges of tires (low and high range)..

Note that new / old / current tech can vary in durability / functionality. Just because it's new tech doesn't necessarily help in an appreciable way. (most newer tech is marginally better, except I was impressed by high end hydraulic brakes - they appear to be more than twice as powerful.) If you're not already an accomplished rider don't worry about getting high end light weight bikes. (not to mention, if you are hefting 400 lbs.. trimming 5 lbs off the bike isn't going to benefit you much..)

And so, you are further armed with information.

Good luck!

Fear not.

A 32mm wide tire can perfectly well carry your weight. I weigh about as much as you do. My bike has 28mm wide tires. I don't get constant pinch flats.

The trick is to fill the 28mm tire to 100psi / 7bar with a floor pump and do so weekly. Air diffuses rapidly out of even butyl tubes. Two weeks without pumping and the tires have lost so much air there's a risk for pinch flats.

For 32mm tires, pump to 90psi / 6 bar or so.

Use the largest and thickest butyl tube you can find that fits to your tires to prevent air from diffusing too quickly. I use Continental 32-47 / 622 inner tubes even though they are not officially "supported" for 28mm wide tires. They work if you know how to install them.

If you use a thin or small butyl tube, you may need to pump as often as twice per week. The thinner and smaller the tube, the faster the air diffusion.

Also, riding technique matters. Use your arms and legs as suspension. If you sit on the saddle and support part of your weight by straight arms and then encounter a bump, you will get a pinch flat.

Also, you need a strategy for pumping up the tires on the road after getting a flat. A good pump will help, but where to get such a pump nowadays when Quickex Quicker Pro is no longer for sale? I don't know. Most mini pumps require over 200 strokes to get any reasonable pressure. A CO₂ inflator kit could help, but 25g CO₂ cartridges are heavy (the 25 grams is the weight of CO₂ not the weight of the whole cartridge) and limit how many times you can repair a flat. Also, CO₂ diffuses out of the tires faster than air, so when having to use CO₂, it is a good idea on the same day to let out the CO₂ and replace it with true air with a floor pump.