mrblue

I am using 25c tires on a set of wheels with internal rim widths of 17mm. I typically run about 80psi in the rear and 75psi in the front. I recently noticed on the sidewall of my tire, it says, "minimum pressure 100psi." Am I going to have problems by not running my tires at the minimum pressure? I would rather not run the tires at 100psi as I really like how the bike feels at the pressure I typically use.

Bill Kapaun

Why are you so intentionally vague?
Brand/model tire?
Your weight?
Ignore List.

Kapusta

Man, who pissed in your cornflakes?

OP: Bill asks relevant questions, here, even though he has no interest in the answers.

Gotta say, 100 psi sounds really high for a min pressure.

hokiefyd 

It's more common for a maximum pressure to be provided than a minimum pressure, but 100 psi is in the ball park for a 25 mm tire. Continental's GP5000 recommends 95-123 psi for the 25 mm size (link here). And their Gatorskin recommends 95-120 psi (link here). Jumping over to Schwalbe, their basic Durano lists 85-115 psi (link here).

Perhaps this is an older tire model, perhaps harkening back to when it was more common practice to inflate tires to about as high as they could go as a common practice?

Personally, I inflate tires (of any size) to a pressure that feels right to me. I generally run as low of a pressure as I think I safely can and still avoid pinch flatting and rolling a tire in a corner. I'm a 240 pound guy, and the narrowest I've ridden is a 28 mm tire (a tire which was really more like 25-26 mm fully inflated). I ran about 60 psi in the front and 80 psi in the rear. 70/80 psi on a 25 mm tire seems like a pressure I'd run, especially if I was any lighter than I am!

HillRider

The only problem you are likely to have from running lower tire pressure is pinch flats. If you are on the light side and ride mostly on smooth roads and haven't had a lot of flats, there should be no reason to run higher pressure. Bike tires aren't like car tires which will get excessively hot and suffer side wall damage if run at too low pressure.

andrewclaus

The manufacturers are concerned about deflection under maximum load. There's enough of a safety factor that those of us carrying normal loads don't worry about it.

In addition to pinch flats, extremely low pressure can allow the tire to slip on the rim when braking, tearing a valve stem.

mrblue

Hi Bill!
The tire is a Vittoria Rubino Pro G+ 2.0. My weight is ~130. My favorite food is Spanish or Brazilian. My eyes are brown and my mom says I have a smile to die for. I grew up on the Atlantic coast and I'm a Capricorn. And according to that cute little placemat at the Chinese buffet I was born in the year of the tiger. I enjoy smooth jazz, long romantic walks on the beach and stimulating conversation over a glass of fine wine. I hope this answers all your questions, Bill. If you're still interested please let me know but be advised, I do not put out on the first date. XOXOXO

cxwrench

Awesome reply to a jackass post. Well done!
As for tire pressure I think you're definitely on the right track. A min pressure of 100psi is ridiculous.

caloso

I weigh 40 pounds heavier than you and usually run 90-95psi in 25mm tires. 100 seems awfully high for a minimum pressure.

Sy Reene

Yeah, Vittorias are always weird that way.. I think my 25mm Corsas indicate a 100-140 range as Min-Max. Originally thought maybe had something to do with supple cotton sidewalls or some other nonsense. I ride mine in the 90-100psi range, though because my weight probably says I should. Curiously Veloflex also have pretty relatively high min-max ratings as well.

SurferRosa

That sounds fine for your weight of 130. I address good, high-pressure road tire inflation as a function of total weight (rider+bike+pack) and tire width. You can calculate it using this site:

Bicycle tire pressure calculator

canklecat

I was surprised to see Continental recommended pressures of 95-120 psi on the GP Classic (700x25 only). I weigh 150, and usually ride around 85 psi rear, 70 psi front (with latex tubes), depending on the road surface. The tires were already good, but in terms of comfort the latex tubes improved the ride even more. No real problems in a year on those tires. I did have one pinch flat last year when I had to dodge a couple of trucks that suddenly converged and forced me to take a line that ran across a brick that fell off one truck trailer bed. No harm to the tire or rim, just a typical snakebite on both sides of the tube. Only snakebite flat I've ever experienced and it took a pretty unusual situation to cause it. I doubt that running higher pressure would have helped in that situation.

Recently most of the nearby pavement has been busted up, resurfaced with the roughest chipseal I've ever encountered, awaiting smoother blacktop which may be months away. So I've been riding at softer pressures for comfort -- and it still shook my headset and rear spokes loose.

On another bike I'm using Soma Supple Vitesse SL tires, 700x23, around 100 psi rear, 85 front. Pretty good, even on rough chipseal. I plan to try latex tubes with those tires as well and maybe reduce the pressure a bit. So far, so good, no problems, no unusual wear or punctures.

djb

yup, you deserve a gold star on your report for that one.

and yes, the minimum pressures on sides of tires are often much higher than what many of us regularly use.
I'm only about 135-140 and the 28mm slicks Ive used for ages have a min. of probably 90 or maybe more marked on them, but I run them regularly in the 75-80 range, which makes a huge difference in riding comfort and cornering grip.
Yes, of course when too low you're cruisin for pinch flats, but you should be able to get a feel for what is too low by experimenting with diff pressures and how things feel. And of course also as noted, some riders "ride heavy" and smack seated heavily into holes and stuff, while others "ride light" and can get away with lower pressures with no issues.

I have seen a touring companion run too low pressures on his very heavily loaded bike for too long and his sidewalls had visual X patterns that showed he was stressing the sidewall too much too often, but this was with a heavy guy and one heck of a heavy loaded bike, so an extreme case. I've never had sidewall issues ever, and the few times Ive had pinch flats was when I've neglected tire pressures for too long and smacked into hard edged potholes commuting pretty hard when commuting and in a rush, so no real surprise.
You learn pretty quickly what is too low for you and your specific tire/pressure/riding conditions mix of stuff.

ps, good luck on getting a date