I've read lots of threads and information on tire pressure. But, there is such a difference I'm still confused. Maybe this forum of elders can help.

The bikes I have use two different size tires: 7:00x23 and 7:00x38. My nominal weight is 190 pounds. I ride on really rough roads and often encounter glass and other sharp things on the road. I currently use max tire label air pressure with no problems but if a lower Safe pressure would bring more comfort I'm all for it.

What should I run in each bike?

I wish it was easy to answer this. https://sheldonbrown.com/tires.html is one of the better sites and they don't actually spell it out.

I use the chart at PSI Rx as a starting point and experiment from there.

There's also a calculator based on it here.

I'm in roughly your weight class.

On my Klein I used to run 700 X 23c tires at 100 psi front and 110 psi rear. On my Bridgestone with 700 X 28c tires I used 90 psi front and rear. for 700 X 38c's I'd use a little less air pressure - maybe 80 or 85 psi.

It comes down to personal preference as long as you have enough psi to avoid pinched flats.

+1 I use that too. Here is the chart. The article is definitely worth reading.



You need to accommodate the differing wheel loads to use the chart:

Experiment. As long as you aren't going so low that you get pinch flats on the rough roads, you are probably OK. I have never found a need to run the max pressure printed on a tire, not even when I weighed 220.

The charts can give you an idea where to start, but you don't need a weatherman to know which way the wind blows.

HawkOwl, I'm close to your weight and I run 15% less than max pressure in both 23Cs on the roadie, 125 PSI max labeled at 100 PSI. The touring bike's tires are 35C and have a labeled range of 60-80 PSI. Unladen I run 60 PSI while 75 PSI worked well in the rear when loaded (no extra front loading).

These pressures have worked well riding Houston's sometimes less than stellar streets.

Brad

Yup, this is the way to go... in practice I just go around 80s, maybe 90's in the back since i ride more upright

If your roads are rough, I would consider swapping the 700 x 23s for a set of 700 x 25s. Doesn't sound like much, but it makes a difference on bad pavement. My two road bikes are currently on Michelin Pro Optimums, 80 psi front/85 psi rear. Very good puncture resistance with these as well.

Note that Donheff's chart is referencing weight for each wheel of course and the rear wheel gets more weight. You can roughly figure your 190 lbs of weight results in 110lb of weight on the rear wheel and 100lb for the front (if your bike weighed about 20lb with tool kit and such). It doesn't matter if you're a few lbs off on those numbers. That would show you good starting points of about 110lb of pressure for the rear and 100 for the front. Dropping each of them 10lbs won't, in my experience, make much difference with regard to flats. It won't be too low to cause a pinch or so low it would pick up anything worse. Tire type and where you ride will have a much greater effect. My wife rides to my right most of the time and gets many more flats than I do because she is more apt to be catching worse junk. I've gotten one flat in the last 1000 mi this summer and she has probably gotten 4 before she decided to put on Gatorskins. The Gatorskins make a huge difference in comparison to our preferred Conti 4000S which I still use for day to day riding. I used my Gators for my recent Century+ ride. I also recommend 25C. The weight difference is minimal, as is the rolling resistance, but the lower pressure really does make the ride more comfortable. With your larger tires you can drop even more pressure before worrying about pinch flats. I can drop my 2.25 studded tires to 15lb if I want. You could drop a set of 25C to 85lb rear (I think) and get away with it safely. The horrible thing about pinch flats is they can happen in multiple places. You can end up with four holes in a tire. I only carry compressed air so they really have to be avoided! Just stay off really nasty roads like they have in Colorado and Alaska and you'll be OK.

Would a summary of: "Use the charts and experiment. Whatever feels good and doesn't give you flats is good." be fairly accurate? That certainly is what I've gotten from this thread. Of course I could be off base a little, or a lot.

The caveat is simply that if you are riding in conditions which present large angular trap rock, etc. then you should forget about comfort achieved by slightly lowered pressure. So long as you've got modern rims and don't blow 'em off at max pressure, that's where i'd be. I just hate pinch flats.

120 psi front and back 700x25's 210 lbs. Done this for 13 years now, never a problem.

I think Hawk Owl's got it. Some folks are tough enough they can run high pressure and not care. Others need to get as gentle a ride as possible. Both of my shoulders have fully torn rotator cuffs. 120 in both tires would be a literal pain for me. A chart...or the max pressure on the tire is a good starting point then experience will eventually take over. I experienced my wife's tire right into a pinch flat at one point...but now we have even more experience and she has as soft a ride as is reasonable. If I'd just pumped to 120 she'd be running for years with unnecessary harshness.

https://www.michelinbicycletire.com/m...rpressure.view

"For riders above 180 lbs, inflate to maximum pressure indicated on tire sidewall"

I don't entirely agree with this fellow:

Running 50F 80R for 32-559 85psi max tires on my long wheelbase bike with lightly-loaded front wheel - I really do need to weigh the bike to figure out the front/rear loading.

Written by lawyers, no doubt.

Pump em up to max.

+ 1 on PSI Rx. I run 35's at 80 PSI. Sidewall max is 110. MUCH more comfortable ride, and no noticeable difference in speed or perceived effort.

I think this is correct. For more opinions and info check this:https://www.bikeforums.net/showthread...for-road-bikes

Guess this group of elders has reinforced general opinion. I'm going to continue using the pressures I've been using since they work.

80 psi in a 700x38c is WAY overinflated. I'm 6'3", 185 lb and run my 650x38b's at 50 and 60 psi, and 700x25c's at 80 and 90. IME, optimal tire pressure is pretty much inversely proportional to width: ie, 38's are 1.5x as wide as 25's, so they should have 2/3 the pressure.

SP
Bend, OR

Why?

SP
Bend, OR