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Thread: Tire pressure

  1. #1
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    Tire pressure

    So me and my 2 boys have been riding for about 5 years now and we still don't understand tire pressures. I've read the forums on rolling resistance and all and we always air up climbing then air down descending. But we air down LOW enough not to get pinch flats and the thinking behind it is we get more traction with wider contact patch. (I ride motorcycles at the track and we Lower pressures for a larger patch]

    Anyhow tire recommends between 35-60 psi for the most part and I aired up my NG super sticky to 35 PSI in th garage yesterday and damn thinks we're hard. So I inflated them to 50 and they were rocks! I was too scarred to blow a tube going higher.

    So what are your thoughts on tire pressure? Inflate between recommend. Or just below?

  2. #2
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    Here is a good read on the basics..

    Trail Tech: Mountain bike tire pressure - all you need to know - BikeRadar

    If you need to run a lower pressure without worrying about pinch flats, deflate the tire and throw some talc powder in there. Seal the tire back up and give it a few good rotations and inflate.

  3. #3
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    In theory, the manufacturer knows their product and should give good guidance, but some brands' recommended pressures are unrealistically high, as you found out, so most riders use pressures low enough to get good traction, but high enough to avoid pinch flats (and not feel too mushy).

    Tire volume, sidewall stiffness/thickness, rider weight and trail conditions all are factors in what pressures work best, so there isn't one ideal number.

    Also I usually use 3-5psi lower front than rear, since the rear tire carries more load, and front cornering/braking traction is more critical (front washout often means a crash).

  4. #4
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    I ride old stuff so the tires have to be a little narrower. I'm running 26x2.1 front and rear.

    I have also lost 65lbs since I started riding. I think rider weight is a big part of it. When I started I was riding at 50 rear and 45 front (240 lbs).

    Went out Monday and ran 40 rear and around 37 in the front (172 lbs). I don't ride aggressively and I pick my line carefully so I could probably get away with less.

    John
    1995 Trek 970 - 80mm Atom Race
    1992 Serotta T-Max - 70mm Z3 Light
    1993 GT All Terra - 46mm Mag 21

  5. #5
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    If you want traction, comfort and sticking in corners you go as low as you can without pinch flats or burping tubeless tires.

    For my 150 pounds that's give or take 22-28 PSI for tubeless tires and 35 - 40 PSI for tube type. These are all 2.2 - 2.4 modern tires with XC, AM and DJ type rims or wheels.

    For some scenarios more air in the tire makes them squirm at the knobs, and less makes the whole tire squirm or move on the rim. I run the most pressure on my dirt jumper because jumps are rather straight and banked turns in the pump track will hold you. The lower pressure is most beneficial when I'm doing climbs and rock gardens with cross country riding.

  6. #6
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    You can lower your tire pressure until you feel rim hits going over rocks or the tire rolling over in cornering through curves. 18 psi front with a tube for me at 175 and 23 rear on techy trails without big speed. With a set of new wide rims at 30mm inside dimension 3-4 psi less.

  7. #7
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    After reading all of this, I think I need to let some air out of my tires.

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    Quote Originally Posted by Clicker1 View Post
    After reading all of this, I think I need to let some air out of my tires.
    Good call

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    Tire pressure

    Good read

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  11. #11
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    Yup, the pressures you mentioned are way high. I'll go up to around 45psi for road. For non technical trail I might let a little air out. As it get bumpier will lower. You'll need to find that minimum you can go. Too low and pinch flatting and even worse denting rims. If you land crooked on a jump too low and you can roll the tire off the rim too. But for me you're talking 25 psi or less for that to happen, unless its something big I smack.

  12. #12
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    Tire pressure

    It should be qualified incl for my earlier post that low pressures assume tubeless if not a fat bike. With my low weight 32-35 PSI would mean occasional pinch flats until I was tubeless with other modern gear.

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    I am a heavier rider and I prefer my tire to be inflated to about 40 lbs, I don't like it when the tire feels squirmy.

    Might be just dumb luck but I only get about one flat per year.......

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