One factor not yet mentioned is that higher pressure not only eliminates pinch flats, it also reduces punctures, as the trash in the road doesn't get stuck in the tire as often. It's one of the reasons I pump up my tires every day.

Maybe he's a dentist who makes a lot of money replacing lost fillings.

Perhaps I missed it, but if the OP is all about speed, or, all about comfort - there may be differing answers?

Some reading I have been doing talks about skinny tires vs fat tires, and that for surfaces less than perfect, the fatter tires actually produce both better comfort and higher speed due to their ability to deflect the bump (or whatnot) rather than the skinny tire bouncing over it.

Over on BROL this topic has been hashed out for many months, with the result leaning to fatter tires.

I switched from 100PSI 20x1.5 Marathons (kept at full pressure) to Big Apples 20x2.00 at 60PSI, and have not lost any speed, and the ride is much more comfortable.

Of note to the OP - you must also consider if fatter tires will even fit on your ride - but I thought it is something to consider and/or read about.

Exactly the psi I've used for my bike plus body weight of 204 lbs. Never had a problem...flats or otherwise. But, I'm going to try the recommended 85 psi front and 129 psi rear just to see.

This question comes up all the time and I usually answer it by explaining what I do and why, but really, why would you want to know what I do with my bike on my local roads, and my riding style? You really want to know what to do with your bike on your roads and your riding style!

The lower pressure limit is where you start getting pinch flats and/or your tyres are rolling badly, and the upper limit is where your tyres blow off the rims or destroy them! You obviously want to choose pressures somewhere between those limits ...

I would suggest that your front pressure should be 10-20 psi less than your rear pressure because more of your weight is on the rear of the bike.

I would also say that comfort is improved by lower pressures but if you go too low then performance will be affected.

Experiment with 90-120 psi in the rear and 80-110 in the front.

The best way to do this is to slightly over-inflate your tyres and go ride one of your typical local routes. Unless your roads are perfectly smooth, it will probably soon be obvious that your pressures are too high. If so, stop and let a small amount of air out of each tyre. Keep doing that until the bike feels good. Use a pressure gauge on the tyres when you get home and see what suited you. (In future make slight increases on those pressures for better roads, or slight decreases for rougher roads and/or wet conditions.)

(In case you are still interested, I tend to use 85-90 psi front, and 95-100 rear. I weigh 215 pounds and some of my local roads are pretty rough so comfort is an important factor. If the roads were better, I'd probably use 95 psi front and 105 rear.)

700x23...............max plus abut 5 front and rear, 187 lbs.

700x 23 120 front and back.

I find that keeping them at 120 really does cut down on the punctures.

115 PSI front and rear, 700x23, oh, and I weigh 135 lbs.. I slip through the wind and dodge raindrops as well...

They don't go flat as much.

Here are the OP’s concerns, back before we got into all the usual banter and tangent posting:


“The bikes I have use two different size tires: 700x23 and 700x38. 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."

Here is an excellent explanation why his current method is working:

"One factor not yet mentioned is that higher pressure not only eliminates pinch flats, it also reduces punctures, as the trash in the road doesn't get stuck in the tire as often. It's one of the reasons I pump up my tires every day."

If you want comfort, a different bike may actually be in order.
One bike runs 23's? Lets face it - bikes running 23's aren't generally conceded to be "comfort bikes."
The other has on 38's? Without knowing what kind of bike he has these tires on, they could allow for some pressure reduction. But based on the road conditions, I'd say keep 'em pumped up.

Comfort is an amorphous quality. It usually expresses a longing for some sort of "different" ride than what one currently knows. But most often, that is found more in the bikes geometry and rider fit/position, than in squishy, softened tires.

Here is what you do, pump the tires to 4lbs short of the max, so if the max is 100PSI, try 96, if that requires too much effort, then try 98, if it still requires too much effort try 99. If 96 is okay, then try 92, you keep going until you find a pressure you like. Do both tires together, once you get a number, go 4lbs less on the front, see how that goes, once you have it down, those are the pressures for that bike. Note a couple of things, if your weight average changes by more then 5lbs or so, you should redo the experiment. Each bike needs to be done separately.

Tires that are pumped up to the max - rock hard - are not really hard like a rock. Why would tires at max pressure be more resistant to punctures from debris?

What's best for me is to pump my tires rock hard before I ride each day. They roll easier IMO.

+1 I think the best way to find out is through experimentation.

Because all but the sharpest stuff rolls off - it tends not to stick. Soft squishy tires, by comparison, tend to grind the stuff in.
This is actually something that has held in cycling for a long time. I understand you are skeptical; part of me still is. But I find that when I put the air to 'em, I get fewer flats.
As for comfort, well, I ride a road bike for both commuting and sport. I don't really expect comfort in terms of a plush or luxurious ride.
Hard tires mean fast and smooth, to me. Comfort is for La-Z-Boy chairs.

Back again since there have been so many follow on posts. Based on what has been posted in this thread it doesn't seem wise to change what I'm doing now. I hate changing tires or fixing flats in the midst of a swarm of mosquitoes while it is misting rain and I'm all hot and sweaty. So, I don't think I'm up for doing something different unless there is a pretty clear consensus on it.

I'm not so sure about the why, but it seems to be true for me. I like a little sag/deflection in my tire but the further I get away from max pressure the more the tire seems prone to flats (not pinch flats).

I am not saying I am right or that even there is a right. Nonetheless, I run my tires at maximum pressure. I pump them before every ride to maximum.

So whats wrong with being right?

This was, at least for me, a pretty interesting read and for the most part pretty civilized.

This is a commonly overlooked factor in tire psi. I've pinch flatted from hitting sharp stones (you just cant dodge 'em all), 3 flats on the back.....all were when tire pressure was below 80lbs. I've since started using the guage and cramming 100psi into tires. Max for these Bontrager B's are 100psi. I weigh 175.

Yes and the closer you get to maximum pressure, the more it seems like your riding on stone tires, there is supposed to be a little deflection in a pneumatic tire, if there isn't then you lose the air suspension from the tire, which means that every imperfection in the road surface is transmitted directly to the rider. This is why we ended up replacing $200 steel and $300 aluminum frames, with $1000 CF frames, attempting to get away from the fact that we are riding on stone hard tires. Run the tires a little softer, I remember 27" straight sided rims, where you could blow a tire off the rim at 90PSI. Personally I prefer a wider tire at a little bit lower pressure....

That sums it up perfectly. I use this chart, and my 25mm front tire is at 70 psi. I have no problems with excessive wear or pinch flats, despite conventional wisdom. Since I've gone to lower pressure, my bike rides much more smoothly. There was recently a rather lengthy thread on this in road, by the way. I could sum it up by saying there are those who will say "pump it to the max", and those who will advocate using the linked chart, and everything in between.
https://www.bikeforums.net/showthread...for-road-bikes

Still not convinced that increased tire pressure has any positive effect on puncture resistance.
Lots of anecdotal testimony that it does but what if I argued that riding my 90psi max front tire at 50psi all year has prevented punctures? Haven't had any punctures but I don't believe either max or minimum pressure prevents punctures.
I have come to accept that 15% tire drop seems to result in optimal pressure for best comfort and performance.
https://www.bikequarterly.com/images/TireDrop.pdf
Those of us riding on not-so-narrow tires can probably take advantage of tire pressures much less than max - I'm 185 and use tires in the 32-40mm width range.

By all means, use what works for you.

I'm re-thinking this. Maybe I'll buy two sets of 23mm tires and tubes. Take the first set and pump them up until they blow, then just back off 5 lbs. of pressure with the other set. If I did this I'm guessing a few things will happen: I'll never have flats; all my dental work will need to be revisited; I'll ride faster than I've ever ridden before; I'll find out if titanium really does take the road buzz down a notch; and I'll annoy the daylights out of those that ride wide tires with less than 80% of the recommended inflation.

You'll need a good pump to get up to burst pressure on "Good" Road tyres.

Some of us can take the "Discomfort" of high pressures and not even notice it- I do not like the "Soggy" feel that low pressures give me. But out of interest- 700x20 tub tyres as used on TT and track racing- And on stiff wheels with NO Give and a frame that is rock solid. How do people get on with those? The 4 that came past me last week uphill on a 5% slope did not look uncomfortable but I dare say that they were not running the 200psi that some track and TT riders use.