Tire pressures for heavy riders?

ch35iM · Dec 8, 2016

I keep searching the threads but I can't find much I can relate to. I'm 220lb with 25mm conti GP 4 seasons. The tire pressure calculator for 60/40 distribution has my rear at around 130 and the front around 85. I'm concerned about the rear as the max inflation is 120psi which is what I've been running it at. My bike shop said I don't need that much and should be around 100 rear. I feel like I try a different pressure every day but can't seem to find one that rolls right without going up to 135. 100 just seems too low

any inputs??

bubble · Dec 8, 2016

ch35iM said:
I keep searching the threads but I can't find much I can relate to. I'm 220lb with 25mm conti GP 4 seasons. The tire pressure calculator for 60/40 distribution has my rear at around 130 and the front around 85. I'm concerned about the rear as the max inflation is 120psi which is what I've been running it at. My bike shop said I don't need that much and should be around 100 rear. I feel like I try a different pressure every day but can't seem to find one that rolls right without going up to 135. 100 just seems too low

any inputs??

~105psi for the rear, a couple less for the front. You increase the risk of flatting on steep descents by running 115+. Moving to a higher volume tire solves a lot of problems.

'Rolls right' can be misleading; if it doesn't corner/brake right you wanna up the pressure, but the losses from friction are fairly linear and fairly subtle below 'ideal' pressure, so they shouldn't be obvious.

I'm ~215lbs myself.

Mike T. · Dec 8, 2016

IMO, if you need more than 100 then you need tires with more volume. And by the word "need" I mean needing more pressure to prevent pinch-flatting. I'm 175 lbs and I use about 80f/90r and they're probably 70/80 before I re-inflate. I don't pinch flat and I'm a "performance" rider and those pressures don't slow me down. Higher pressures can make you slower by bouncing you up in the air and by rider fatigue from a harsh ride.

Peter P. · Dec 8, 2016

Mike T. said:
IMO, if you need more than 100 then you need tires with more volume.

Exactly. If you need more pressure, you need a larger tire. And if your bike will only fit 25mm tires when you need larger tires, then you NEED a different bike.

I'll admit, 220lbs. with 25mm tires-start thinking about upsizing.

Mike T. · Dec 8, 2016

Peter P. said:
And if your bike will only fit 25mm tires when you need larger tires, then you NEED a different bike.

That would be tough medicine to swallow if you were 200lb+ and had been sold a road bike that was really designed for sub-160lb road racers (low spoke numbers, narrow tires, low tire clearances).

dcgriz · Dec 8, 2016

ch35iM said:
I keep searching the threads but I can't find much I can relate to. I'm 220lb with 25mm conti GP 4 seasons. The tire pressure calculator for 60/40 distribution has my rear at around 130 and the front around 85. I'm concerned about the rear as the max inflation is 120psi which is what I've been running it at. My bike shop said I don't need that much and should be around 100 rear. I feel like I try a different pressure every day but can't seem to find one that rolls right without going up to 135. 100 just seems too low

any inputs??

The calculator you are refering to is based on Frank Berto's tire pressure charts that focused on 15% tire drop. Berto made the chart in the 1990s, when tires were much narrower and predominantly with stiffer sidewalls than current trends dictate. The 15% as desirable tire drop was based on the recommendations of several tire manufacturers, but not on actual testing. So the chart shows how much you need to inflate an average 1990s tire to achieve a tire drop of 15% – nothing less and nothing more.

Berto’s chart still is a good starting point. Inflate your tires to the pressures it recommends, then experiment by adding or letting out some air.

The minimum safe pressure is higher for more supple casings. Stiff casings hold up the bike more, and thus require less air pressure.

Don’t run your tires so low that the casing cords start to break. That happens only at very low pressures, but if you start seeing multiple lines across the casing where cords have broken, inflate the tires a bit more.

See what feels best to you. That is the optimum tire pressure for you. Don’t worry about tire pressure any further!

Here is a summary in two sentences:

1. Ride the tire pressure that feels good to you.
2. When in doubt, let out some air.

IMO, you probably will end up balancing performance (aka "feel") and comfort at around 85 psi for the front and 100 psi for the rear at your 220 lbs body weight and 25mm Contis GP 4S. Noone but you will be the better judge on that. Of note is that the next size up of GP 4S labeled as 28mm only measures 26.5 mm on 17mm rims so when time comes to replace tires these may be another option at even lower inflation presure.

Lombard · Dec 8, 2016

dcgriz said:
Here is a summary in two sentences:

1. Ride the tire pressure that feels good to you.
2. When in doubt, let out some air.

Good advice, DC. But you missed the rhyme on 2) When in doubt, let some air out.

ch35iM, is this the link you used:

Bicycle tire pressure calculator

Try entering 28mm tires and see what you get. If you can fit them between your stays, by all means this is a good way to go. I am 170lbs. and went to 28mm. I will never go back. The ride is just so much nicer!

cobra_kai · Dec 8, 2016

If you have a pair of calipers you may want to measure how wide your tires actually are. My 25mm GP4000 measure about 27.5 mm on 20 mm wide internal rims, and 25 mm Michelin Pro4 Endurance measure 28 mm on 18 mm wide internal rims.

ch35iM · Dec 8, 2016

Lombard said:
Good advice, DC. But you missed the rhyme on 2) When in doubt, let some air out.

ch35iM, is this the link you used:

Bicycle tire pressure calculator

Try entering 28mm tires and see what you get. If you can fit them between your stays, by all means this is a good way to go. I am 170lbs. and went to 28mm. I will never go back. The ride is just so much nicer!

thats the link. And I was also thinking of going 28s. I can definitely squeeze them. My current rear tire is shot after 900 miles at max pressure.... tread started breaking off... maybe I am too high

Migen21 · Dec 9, 2016

I'm a little heavier than you at 225 or so.

I can't comprehend riding at pressures that high.

I run 25 4 seasons as well (sometimes 28s). If my rear tire is over 100 psi I'm pretty miserable.

My goto pressure is 75f/85r. I go by feel to determine when they need a little air.

I put a premium on comfort. I go as low as I can and still be comfortable that I won't pinch flat.

Sent from my Pixel using Tapatalk

Lombard · Dec 9, 2016

ch35iM said:
thats the link. And I was also thinking of going 28s. I can definitely squeeze them. My current rear tire is shot after 900 miles at max pressure.... tread started breaking off... maybe I am too high

Really shot after only 900 miles? Max pressure won't do this and neither will 220lbs. Only poor quality will. If that ever happened to me, I would never use that brand of tire again.

ch35iM · Dec 9, 2016

Lombard said:
Really shot after only 900 miles? Max pressure won't do this and neither will 220lbs. Only poor quality will. If that ever happened to me, I would never use that brand of tire again.

I would tend to agree but I think I am the only one that had a bad experience with this tire

Migen21 said:
I'm a little heavier than you at 225 or so.

I can't comprehend riding at pressures that high.

I run 25 4 seasons as well (sometimes 28s). If my rear tire is over 100 psi I'm pretty miserable.

My goto pressure is 75f/85r. I go by feel to determine when they need a little air.

I put a premium on comfort. I go as low as I can and still be comfortable that I won't pinch flat.

Sent from my Pixel using Tapatalk

Maybe ill try something like that later today and see how it feels, I never thought of going that low..

Soonerinfrisco · Dec 14, 2016

Wow my head is now spinning! Been playing with my new HED Plus Belgium wheels and pressures. Running Spec Roubaix 23/25 tires. I weigh 260 lbs or so and ride a Roubaix. I rode with about 90 psi in rear last night and probably same in front. The tires felt OK but my gut was a bit worried that I was too low. thoughts? Is 90 psi too low for a guy my size?

Mike T. · Dec 14, 2016

IMO 25 (and especially 23) is too low for a guy your size. I'll bet your bike won't take the tires that I think you should have.

Migen21 · Dec 14, 2016

I'm close to that weight, and rode Belgium Plus with Conti 4 Seasons 25mm just fine. I rode them at about 75f 85r and no issues with pinch flats.

This of course depends now how 'heavy' you ride, and the conditions. If you are on a relatively clean surface and are good about un-weighting the bike over 'problems', you can probably get away with 25's.

That said, you are going to be a lot more comfortable (both physically, and for flat avoidance) running 28s.

Jay Strongbow · Dec 15, 2016

Lombard said:
Really shot after only 900 miles? Max pressure won't do this and neither will 220lbs. Only poor quality will. If that ever happened to me, I would never use that brand of tire again.

um, no. Tires definitely wear out faster at higher pressure.

Lombard · Dec 15, 2016

Jay Strongbow said:
um, no. Tires definitely wear out faster at higher pressure.

Seriously? At higher pressure or at pressures that are too high? My guess is that it is not an even curve. I would also believe that tires will wear out faster at too low pressure or anything outside the realm of normal.

I would say that unless the pressure is way outside that realm, 900 miles is highly unusual.

cxwrench · Dec 19, 2016

ch35iM said:
I keep searching the threads but I can't find much I can relate to. I'm 220lb with 25mm conti GP 4 seasons. The tire pressure calculator for 60/40 distribution has my rear at around 130 and the front around 85. I'm concerned about the rear as the max inflation is 120psi which is what I've been running it at. My bike shop said I don't need that much and should be around 100 rear. I feel like I try a different pressure every day but can't seem to find one that rolls right without going up to 135. 100 just seems too low

any inputs??

Seems=feels. You 'think' that harder should be faster because it 'feels' fast. In reality it's slower because it bounces off the bumps and texture of the pavement. It also reduces traction in corners. Physics (do some research) says lower pressures (down to the point you where you waste energy to hysteresis) are faster.
Think of it this way: Push a shopping cart on the smooth grocery store floor, then push it outside to the parking lot. Rougher surface, same hard wheel. Takes more push to make it move, right? The bicycle equivalent would be a wood track and then the road.
That's obviously an extreme example, but the idea is the same, just not as much difference.

Lombard · Dec 19, 2016

cxwrench said:
Think of it this way: Push a shopping cart on the smooth grocery store floor, then push it outside to the parking lot. Rougher surface, same hard wheel. Takes more push to make it move, right? The bicycle equivalent would be a wood track and then the road.
That's obviously an extreme example, but the idea is the same, just not as much difference.

Good analogy! This is why climbing a hill on hardpack requires more energy than on pavement. And in the real world, roads have imperfections anyway.

If roads were glass, then higher pressures would be faster. Of course then there would also be the obvious problem of stopping or lack thereof.

Interestingly, my knobby tired mountain bike rolls easier on dirt than on pavement. Or maybe it just seems that way?

bmach · Dec 19, 2016

Put them at 100psi and try riding. If you pinch flat then you need more if you don't you can try a little less or just stay there. But at 130psi you should just use a solid tire. Just my two cents.

Tire pressures for heavy riders?

ch35iM

bubble

Mike T.

Peter P.

Mike T.

dcgriz

Lombard

cobra_kai

ch35iM

Migen21

Lombard

ch35iM

Soonerinfrisco

Mike T.

Migen21

Jay Strongbow

Lombard

cxwrench

Lombard

bmach

Top Contributors this Month

Recommended Communities