Roadie607

I know this issue has been talked to death but I want to hear some current viewpoints on the age old question of optimal tire pressure, optimal being lowest rolling resistance to a reasonable point where the tire isn't bouncing off of every little bump in the road. I read a bunch of old threads which are a bit dated, but what I could gather is that the optimal tire pressure is directly correlated to the weight of the rider. So a lighter rider's tire pressure should be a lower PSI and a heavier rider's pressure should be a higher PSI. Is this correct? I also noticed that the newer tire designs are reducing the min/max pressure ranges. So, does all this mean that the industry has come to the conclusion that the tire pressure to rolling resistance graph is not a linear relationship, but rather one that plateaus after a certain point? On the other hand, there are a lot of people who still assert that rolling resistance and tire pressure have a linear relationship at the high end of the spectrum (120 to 130 PSI etc.) What do you guys think?

BTW, I am 160 lbs fully kitted, riding Vittoria Zaffiros in a 23 width at 120 PSI front and rear. However, some manufacturers like Michelin suggest around 10-20 pounds less than that for my weight. Is this correct?

RoadTire 

Oh, good. This is the 41. It's gonna be a free for all.

Any research, data, or opinions over 29 days old is automatically stale and not relevent by todays standards.

hueyhoolihan

IME, max tire pressure as listed by the manufacturer is always high enough.

PSI, for me, is as low as i can get it without having too many pinch flats. "too many" is personal of course, but i weigh 150lbs and run about 75PSI in a 25mm 700c tire. performance and comfort are both at a maximum for me using this formula with a mix of smooth and chip-seal pavement.

Doolittle

Maybe! I think it really depends on the roads you're riding on more than anything. I usually ride 25c tires at around 80-90 PSI, but I ride on a lot of dirt roads so that suits me well. I would ride larger tires if they fit into my frame. I'm of the opinion that most people would not notice a difference between 110 PSI and 120 PSI in most circumstances. I think the best approach is to experiment with pressures a bit (easy to do) and adjust them according to road conditions. From what I understand, higher pressure would be faster on very smooth surfaces, but real roads are often not so smooth.

carpediemracing 

Weight is one factor in determining tire pressure.

With clinchers the rim is a huge factor in tire pressure. If you're using "normal" width rims, 21mm on the outside, then you're realistically in the 100-120 psi range. If you're using a "wide" rim, 23mm, then you can run substantially lower, like 80-100 psi for a high range, 65-85 psi on the low range. This is based on my experience at your weight and on similar size tires.

I'm old school and prefer a higher pressure. I also tend to ride pretty smooth surfaces so rough stuff rolling resistance isn't as critical to me. Finally I tend to be a bit violent on the bike out of the saddle, I am used to cornering with higher pressures, and I feel more in control with a higher pressure tire.

When I had 21mm rims I'd usually do 105-120psi for the tires, about 5 psi difference between the front and rear (just because - I actually couldn't really tell lol). At a higher weight than you, 23mm rim, 23c tires, I usually run 95-105 psi, and that's considered high. I've run as low as 65 psi but find that the tire feels too mushy in hard corners. My weight ranged from 130 to 215 for those pressures, over the course of 25 years.

With wider tires or wider rims you should be able to reduce tire pressure. 25c tires allow you to reduce pressure substantially but for road use I don't know what. I do know that pros like Tom Boonen were running in the high 50s psi for Paris Roubaix (if you look up his bike I think Velonews had tire pressures for a few years).

If you're riding on very rough surfaces then tire pressure is a major, major, major part in determining rolling resistance, and a really rough surface (rumble strip) can more than double the amount of power required to ride at a certain speed (183w to 473w to maintain 16 mph). More here:
https://janheine.wordpress.com/2012/0...ension-losses/

That blog also has the following on width:
https://janheine.wordpress.com/2014/0...e-is-too-wide/
and the downsides of going super wide:
https://janheine.wordpress.com/2012/0...of-wide-tires/

For me my bikes barely take a 23c tire so I haven't even tried a 25c. For now it's just not in the books. With the 23c tires I feel pretty comfortable with the wide range of tire pressures I've tried, from the low of 65 psi to the high of about 115 psi.

SpeshulEd 

I usually start at the max and then ease off a bit as I ride the tire more. I'm 190 (fatty!) at the moment, riding on 23mm GP4KSs and usually put between 90-100 in the front and 100-110 in the back. In my 25mm Gatorskins on the commuter, I roll at 80 in the front, 90 in the back.

I air up before each ride and so far, no pinch flats.

Jed19

At 160 Ibs, 120 PSI front and back just screams too much pressure. I am 210 Ibs right now, and I run 110/front 120/rear on 23mms, and 100/front 110/rear on 25mms.

And I have been known to even let out some air during rides, depending on certain road conditions.

OldsCOOL

I'm 175 and run 110psi in the Michelin Krylion 23's with good effect and ride quality. Surfaces here are smooth and have had amazingly few flats.

clausen

I set the pressure so I get the ride quality I am looking for. With 23mm tires usually 100-110 in the rear tire, depending on what tire I'm using. I think 120 is too high for your weight and tires, try dropping it to 100/105 and than to 95/100. Your ride quality will be much better and you won't notice a difference in speed.

MonkeyBiker

Good read. How about 120lb guy with 25mm tires?

darb85

no more than 100 psi

hueyhoolihan

if i were 120 on 25's i wouldn't be surprised if i were down in high 60's.

after having to fix a flat on a mountain ride and having to use my POS handpump on the tire, i raced home some guy who passed me (you know how it is). when i got home i checked the pressure, turns out i had only gotten 50PSI in it. yea, it was soft, no doubt would have pinch flatted it had i hit anything, but it really didn't slow me down... i was pretty surprised.

datlas 

Drop your pressure to around 100.

Do it now and thank me later.

PatrickGSR94

I run 85-90 front and around 100 in the rear on GP4Season 25's. Used to have stock 21mm rims and just switched to lighter Vuelta 20mm rims.

UnfilteredDregs

I'm 205# running 28mm tubeless at 65/75 front/rear. Very nice. Rims are 25mm wide. I'd like to know what to look for to ensure I'm at an optimal pressure. Feels great.

link0

150lbs rider on 23mm tires: 80psi front and 90psi rear.

coasting 

i don't know why people think heavy riders should have really pumped up tires. i like 90 front 100 back. more than that and it feels a bit harsh.

datlas 

How fat are you?

rpenmanparker 

I'm at my high weight of 170 lb now and riding 23 mm GP4KSs on standard narrow rims at 90/95 front/rear. I used to ride 110 front and rear and learned that was silly by reading here. No pinch flats at the lower pressures after a couple of years. Mixed city streets with plenty of rough stuff.

coasting 

mind your own beeswax.

datlas 

Sorry, did I touch a nerve??

Jiggle

My bike and rider weight is exactly 170lbs. I ride a 30mm on the rear at 65psi and a 25mm on the front at 70psi. Rims are 16mm interior width.

datlas 

I was going to post this earlier. This chart is not gospel, but a good starting point:

rpenmanparker 

Not to be argumentative and with an authority like Michelin to boot, but thtose pressures seem a bit high by today's standards. Isn't there a formuma floating around that gives lower pressures?

coasting 

that chart is bunkham.