Pressure for fat road tires?- Mtbr.com
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  1. #1
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    Pressure for fat road tires?

    My spousal critter has a new Orbea ebike (about 35 pounds? maybe 40), isn't carrying any gear and weighs 150 pounds. After the first commute, she complains that it rides roughly over bumps/cracks, tree route ridges in the asphalt, RR track and stray pebbles on the street. I didn't measure the pressure, but the shop probably inflated the 50 mm (x 700c) tires to at least 70 PSI, at a guess from the quite firm feel of them.

    Seems like it is defeating the purpose of the wide tires to run them that hard. Speed is not an issue, since she only wants to go 12 to 15 MPH. She could go on multiple rides without draining the battery, so no need for trying to eke out the last bit of rolling resistance. Obviously, we don't want to get down to having the tires wobbling (did that commuting on my fat knobbies recently) or risking pinch flats. For an all-up weight of 190 pounds, what PSI would you start with for experimenting with a better (less jarring) ride on the road and good handling?

  2. #2
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    I'd start somewhere around 35-40 psi.
    I brake for stinkbugs

  3. #3
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    I can get by with 35 psi on the front of my road / gravel bike with a 42 mm tire. I bet with 50mm and a light rider you are looking at mtb pressures (25 front / 35 rear).

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    Quote Originally Posted by BuckRimfire View Post
    My spousal critter has a new Orbea ebike (about 35 pounds? maybe 40), isn't carrying any gear and weighs 150 pounds. After the first commute, she complains that it rides roughly over bumps/cracks, tree route ridges in the asphalt, RR track and stray pebbles on the street. I didn't measure the pressure, but the shop probably inflated the 50 mm (x 700c) tires to at least 70 PSI, at a guess from the quite firm feel of them.

    Seems like it is defeating the purpose of the wide tires to run them that hard. Speed is not an issue, since she only wants to go 12 to 15 MPH. She could go on multiple rides without draining the battery, so no need for trying to eke out the last bit of rolling resistance. Obviously, we don't want to get down to having the tires wobbling (did that commuting on my fat knobbies recently) or risking pinch flats. For an all-up weight of 190 pounds, what PSI would you start with for experimenting with a better (less jarring) ride on the road and good handling?
    We need more information. What do you mean when you say "fat road tire" (exact size)? I don't know what tire your running (this information would help too) but they all will have a recommended pressure range printed on the sidewalls.
    Mole

  5. #5
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    He told you the tire size. 50mm x 700c.

  6. #6
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    Quote Originally Posted by cassieno View Post
    He told you the tire size. 50mm x 700c.
    Thanks, my bad!
    Mole

  7. #7
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    30 to 40 should be about right.

    Given that is an E-bike you can probably prioritize comfort over rolling resistance.
    "The best pace is suicide pace, and today is a good day to die." Steve Prefontaine

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    Quote Originally Posted by MRMOLE View Post
    We need more information. What do you mean when you say "fat road tire" (exact size)? I don't know what tire your running (this information would help too) but they all will have a recommended pressure range printed on the sidewalls.
    Mole
    The tires are Kenda, no model name on the sidewall but molded little number 1172. That looks like a Kenda stock number, as seen at their website, but that number doesn't appear in the list.

    https://bicycle.kendatire.com/en-us/find-a-tire/

  9. #9
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    Quote Originally Posted by BuckRimfire View Post
    The tires are Kenda, no model name on the sidewall but molded little number 1172. That looks like a Kenda stock number, as seen at their website, but that number doesn't appear in the list.

    https://bicycle.kendatire.com/en-us/find-a-tire/
    Pressure for fat road tires?-003.jpg

    This is what I was thinking you would find on the sidewall (700x60 Kenda Karma pictured). After it was pointed out to me that I missed the tire size I did go to the Orbea site and figured out which bike and what tire you were dealing with. From there I snooped around the Kenda site but couldn't find the tire either so it's probably an OEM item. Similar sized tires on the site were rated @ either 60psi or 80psi and what I found strange is all the tires only had one recommended pressure (which I'm assuming is the max rating). Out of curiosity I'd call the shop that set up the bike to find out how they arrived at a tire pressure setting. I would think something around 40psi sounds reasonable/safe/more cushy (for a tire that size).
    Mole

  10. #10
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    The recommended psi on the sidewall has nothing to do with what psi you should actually use, they were written by lawyers to prevent liable suits.
    I brake for stinkbugs

  11. #11
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    Quote Originally Posted by J.B. Weld View Post
    The recommended psi on the sidewall has nothing to do with what psi you should actually use, they were written by lawyers to prevent liable suits.
    Yep, it's only a good starting point but useful information IMO. I'm sure the Lawyers are responsible for the single psi ratings on the site now.
    Mole

  12. #12
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    Quote Originally Posted by J.B. Weld View Post
    I'd start somewhere around 35-40 psi.
    This. I run Maxxis Hookworms (26X2.5) on my 'road' bike. Ride gets a bit harsh beyond 37 PSI.

    Sent from my moto g(7) power using Tapatalk

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