rbent Forum - Tire inflation info

power_bent Five Star Member rbent member Posts: 632	Tire inflation info May 16^th, 2011, 1:04am http://www.bikequarterly.com/images/TireDrop.pdf Check it out..
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aikigreg Moderator recumbent ninja Posts: 3685	Re: Tire inflation info Reply #1 - May 16^th, 2011, 8:55am And apparently us fatties over 155 pounds have to inflate the tire over the rated pressure for the wheel
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power_bent Five Star Member rbent member Posts: 632	Re: Tire inflation info Reply #2 - May 16^th, 2011, 10:18am Quote from aikigreg on May 16^th, 2011, 8:55am: And apparently us fatties over 155 pounds have to inflate the tire over the rated pressure for the wheel
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FlyingLaZBoy

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Re: Tire inflation info
Reply #3 - May 16^th, 2011, 3:16pm

Quote from aikigreg on May 16^th, 2011, 8:55am:

And apparently us fatties over 155 pounds have to inflate the tire over the rated pressure for the wheel Grin

'fraid you're reading the chart wrong, Greg... the bottom (horiz.) scale is WHEEL LOAD, not total weight... Smiley

Granted, it still doesn't go high enough for ME, but...... being a linear-looking relationship, it's easy to extrapolate...

I'm not sure what a B-brand hiracer load distribution is, but it's probably about 60 (rear) :40 (front). The Stratus XP is ~ 67:33, and the Xstream is closer to 75:25.

So if combined rider/stuff/bike weight is ~245 pounds and you're on 28mm tires on a 60:40 hiracer, the chart indicates 110 psi for the rear tire (~145 pounds), and ~75psi on the front (~100 pounds)...

On the other hand, if you're Jay on the XStream on 25mm tires, tipping the total scale at MAYBE 150 pounds combined, he should be running 85 psi on the rear, and no pressure whatsoever on the front... Cheesy

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« Last Edit: May 16^th, 2011, 3:26pm by FlyingLaZBoy »

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TonyWard

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Re: Tire inflation info
Reply #4 - May 16^th, 2011, 4:37pm

Quote from FlyingLaZBoy on May 16^th, 2011, 3:16pm:

Quote from aikigreg on May 16^th, 2011, 8:55am:

And apparently us fatties over 155 pounds have to inflate the tire over the rated pressure for the wheel Grin

On the other hand, if you're Jay on the XStream on 25mm tires, tipping the total scale at MAYBE 150 pounds combined, he should be running 85 psi on the rear, and no pressure whatsoever on the front... Cheesy

I'm not sure why he even carries around that front wheel - seems like dead weight to me!!!

PS: he had a full water bottle in his bag Saturday but I never saw him use it - he must be training for something

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« Last Edit: May 16^th, 2011, 4:38pm by TonyWard »

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FlyingLaZBoy

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Re: Tire inflation info
Reply #5 - May 16^th, 2011, 4:57pm

Just for fun, I extrapolated the Berto chart for us heavier folks...

First, find your overall combined weight along the top of this table, then figure out what approximate rear/front load ratio you have between your wheels (trike riders, I can't help you... Cool

). Find the two loads in the weight columns that apply.

Now, from the chart, choose the line for the size tire you're running, and the load on it along the bottom, then find the "recommended" pressure on the left.

Basically for heavier folks, this says stay with 1.25 (32mm) or larger tires... but regardless, this should serve as a handy starting point for tire pressure -- adjust as needed, or as they say, "YMMV"... Smiley

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« Last Edit: May 21^st, 2011, 2:41pm by FlyingLaZBoy »

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jayg

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Re: Tire inflation info
Reply #6 - May 16^th, 2011, 5:22pm

Quote from FlyingLaZBoy on May 16^th, 2011, 3:16pm:

'fraid you're reading the chart wrong, Greg... the bottom (horiz.) scale is WHEEL LOAD, not total weight... Smiley

Granted, it still doesn't go high enough for ME, but...... being a linear-looking relationship, it's easy to extrapolate...

I don't know Paul. May be wildly nonlinear past the chart limits. Would probably be safer to trade your bike in on a trike so wheel loads will be within chart range. Cheesy

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power_bent Five Star Member rbent member Posts: 632	Re: Tire inflation info Reply #7 - May 16^th, 2011, 8:06pm Man O man ,I'm in trouble here!!!!!
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TonyWard Five Star Member rbent member Posts: 960	Re: Tire inflation info Reply #8 - May 16^th, 2011, 8:49pm I don't know about anyone else but when I need to haul a$$ I just make two trips.
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rmillay Five Star Member rbent member; go Clowns! Posts: 2201	Re: Tire inflation info Reply #9 - May 16^th, 2011, 10:07pm I seem to have ridden about 30,000 miles on underinflated tires. It's a wonder I survived!
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FlyingLaZBoy Moderator '16 ICE SprintX fs, '16 Rocket, '12 KHS Mocha Posts: 5803	Re: Tire inflation info Reply #10 - May 17^th, 2011, 1:51pm It would probably reduce the vibration transfer up front, but I'm a little wary about dropping a 1.1" tire down to 50psi and then getting a pinch flat...
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FlyingLaZBoy

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Re: Tire inflation info
Reply #11 - May 18^th, 2011, 7:53am

Just for funsies, I dropped the pressure in the front 1.1" Durano from its usual 110 down to 80psi, for the Mesquite ride last night. It was subtle, and not exactly a "double-blind test" (You know how it is, you make a change, then your mind somewhat artificially magnifies any expected changes that you think you sense...), but I have the impression that it significantly reduced the road vibration transfer to the bars and pedals (especially on the chipseal of the Hwy80 service road), with negligible effect on speed, positive or negative. And I didn't pinch flat on the nasty tracks at Scyene Rd.

Regardless of real effect or not, think I'll keep it there for a while...

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Ric_Clark

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Re: Tire inflation info
Reply #12 - May 18^th, 2011, 9:58am

Quote from jayg on May 16^th, 2011, 5:22pm:

Quote from FlyingLaZBoy on May 16^th, 2011, 3:16pm:

'fraid you're reading the chart wrong, Greg... the bottom (horiz.) scale is WHEEL LOAD, not total weight... Smiley

Granted, it still doesn't go high enough for ME, but...... being a linear-looking relationship, it's easy to extrapolate...

I don't know Paul. May be wildly nonlinear past the chart limits. Would probably be safer to trade your bike in on a trike so wheel loads will be within chart range. Cheesy

TRIKES are good ridinnnnnnnnnnnnnnnn.

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Ric Clark

I will persist until I succeed...

Gig em AGGIES, Smiley

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bob wand Ex Member	Re: Tire inflation info Reply #13 - May 19^th, 2011, 10:50pm Much to do about nothing
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aikigreg Moderator recumbent ninja Posts: 3685	Re: Tire inflation info Reply #14 - May 20^th, 2011, 8:44am Quote from bob wand on May 19^th, 2011, 10:50pm: Much to do about nothing I wouldn't say that. While I've not calculated it scientifically as above, reducing tire pressure over rough roads has made a noticeable increase in comfort.
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