Optimal pressure for a 700x26 tire
 

I have been watching recently videos about lowering the pressure of your tires to get better performance. The sidewalls of my Roadsport 700x26 tires read 100-120psi. I have used the SRAM pressure calculator and it goes as low as 70psi! Is that safe? Would a pressure that low mean looking for trouble?

Depends on your combined weight, road conditions, speeds, tire/tube?, measured width, etc. I go as low as 80 in the front w/o trouble..

Don't worry about the minimum pressure. That is probably just there to make sure you get the tire seated or so customers don't complain about pinch flats. But if you are light enough to get a 70 PSI recommendation you aren't going to pinch flat - that's part of the calculation.

Ask smd4 what pressure he’s running and then subtract 30%.

Otherwise just follow the online calculator’s recommendation and adjust up or down in small increments as needed.

Google 15% tire drop chart. Then do the math. :thumb:

You can try it out and find out for yourself. You should be able to tell pretty quick if it isn't a tire pressure you wish to ride. Your legs will tell you if they like pedaling at that pressure or your butt will tell you if the tire pressure is too squirrely on turns.

If these are tubed tires and you have pinch flats, then the PSI is probably too low for your conditions.

Here's another one:
https://silca.cc/pages/app-tire-pressure-calculator

I've been using the zipp pressure calculator for a couple of years, since I switched to tubeless. They recommend 52/56 psi for my 28mm tires on 25mm IW hookless rims. No problem.

Some of the pressures recommended for tubed setups might be prone to pinch flats.

That depends. If you watch where you are going, you can get away with pressures quite low without getting pinch flats. If you hit a large enough pothole, you can get a pinch flat even at bomber pressures.

I was going to add that some riders are hard on wheels and more prone to pinch flat (dent rims, cut and bruise tires, etc.). All who've mechanic'd a while know some of those. Those riders need more pressure than I do at my weight and on the same roads. That said, I don't like squishy tires unless I'm on ice or other very slippery surfaces and don't come close to pinch flat pressures.

Yep, some people ride heavier than their weight.

What do you consider "squishy"? I ride 70F/80R on my 28's and 45F/50R on my 42's and I'm around 175lbs. That is a little higher than what the calculators display, but I'm lazy and only check pressures once a week or so.

+1 for trial & error

fwiw
I do like the front approx. 10psi lower than the rear
I'm about 223 lbs, then add clothes, a 20lb bike & a 5lb trunk so at about 250lbs I like my rear 25mm tire to be about 100psi, maybe 110 tops, but no higher. the charts say I should go higher but my trial & error has brought me to about 100 rear / 90 front

At 170lbs I ride 80 front 85 rear on 25c Vittoria Rubinos.

yeah that is good!

mine came out to
front 94.2 psi
rear 100.2 psi

which is so close to what I use
front 90
rear 100

Ooof. I can't imagine how sluggish my wheels would feel if I ever let the air out of them to 70 psi...

Huh. Just tried this for my old Centurion Ironman with Wolber Alpine rims and 28mm tires, and came up with

PRESSURE SUGGESTIONS
FRONT TIRE
74.8 psi
REAR TIRE
79.6 psi

So, 75 and 80 psi. Just means I can lay off the upper body workout when trying to get to 90 psi ....

You shouldn't round those numbers -- it will change everything.

You might be pleasantly surprised.

According to the SRAM/Zipp pressure calculator, running numbers for an 18lb bike wearing standard tubed 26mm tires for dry road on 19mm hooked rims:
140lb rider =70psi front/ 74psi rear
150lb rider = 71psi front/76psi rear
160lb rider = 73psi front/78psi rear
170lb rider = 75psi front/80psi rear

I am 165lbs and run 28mm tubeless road tires on 23mm i.d. hookless rims at around 60psi. The calculator suggests I could go 56/60psi for dry and 51/54psi for wet conditions. My floor pump gauge is not accurate enough to dial this in that tight, so I just generally aim for 60 and call it a day. The ride is fine at that pressure and still feels fast.

The good thing about the Silca one is it has a setting for surface, these: https://cdn.shopify.com/s/files/1/03...Guide.pdf?8341

Being in the city I use "worn pavement / some cracks" which lowers the pressure slightly.
I think in theory this is faster because the tyre absorbs more of the road vibration, it's also a better ride quality.