Running tires at the sidewall max PSI

Discussion in 'The Perfect Line and Other Riding Myths' started by antonac, Mar 21, 2012.

  1. antonac

    antonac Commuter

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    Am I the only one who thinks that this completely idiotic, and arguably dangerous? I run my KLR's front at 25-28psi cold with no load where they're rated for mid-30s, and I know of compatible tires with sidewall ratings well into the 40s.

    http://www.msgroup.org/Tip.aspx?Num=009

    They're talking about running this in the winter, no less, and give no other justification than "for longest tire life". On a safety site. I think maybe someone needs to have a word with these guys?
    #1
  2. duck

    duck Banned

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    Despite the URL that site is mostly the OPINIONS of one guy. He posts many controversial things there. (i.e. bullshit)
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  3. perterra

    perterra -. --- .--. .

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    Curious as to why it's dangerous?


    I run lower off road, on the highway I pretty much run the max and have for more years than I can remember.
    #3
  4. larryboy

    larryboy Chopper Rider

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    He's right, whomever he is. Remember the flipping Exploders on Firestones? Nothing wrong with the tire, the low pressure on the door tag and in the owners manual is what got them.

    Tires run cooler, last longer and get better fuel economy at the recommended pressure that is stamped on the tire.

    Can you get away with less pressure for a better ride and more traction? Yes.
    #4
  5. duck

    duck Banned

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    If I run my front PR2s at the max sidewall pressure then the tire is too hard and the front end wanders all over the place. How is having less control safer?
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  6. perterra

    perterra -. --- .--. .

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    Why does too hard make it wander? Tire profile?

    Never had that issue, I have run at over the max load for days on end. And can tell you from trailer tires, heat build up here can kill a tire quick and I dont mean wear out the tread, I mean letting go all at once.
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  7. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Depends on the tire manufacturer's recommendations and the tire pressure rise with riding.

    The 1973 tag on my bike has 25/27 psi for the tire pressures, but that was for tires from that era. My current Avons recommend 32/36 psi and the bike feels better.

    One rule of thumb we used to use back when was the "10% rule". Measure the tire pressures COLD. Go out and run them at highway speeds for 10-20 miles and measure the tire pressures HOT. If the pressure increase is less than 10%, your cold pressure is too high and the tire is not heating up enough. If it's more than 10%, your cold pressure is too low and the tire is heating up too much. Adjust the COLD pressures to get a 10% rise. The reason is sidewall flexing. Or so the theory was back then.

    Otherwise, :deal
    #7
  8. thehomealien

    thehomealien Been here awhile

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    This ^^^

    Evaluate his statements carefully. What he says about tire pressure may be correct, but if so, it's only by chance. He writes some long, detailed, and seriously confused articles.
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  9. JamesG

    JamesG Rabid Poster

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    Its unwise to make blanket statements.

    All tires have different properties and behaviors. And motorcycles react differently to those changes.

    Bolded for irony. :D
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  10. HairBear

    HairBear I'm a Grandpa

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    Odd statement when the sticker on my KLR says 21psi.
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  11. daveinva

    daveinva Been here awhile

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    Hmmm. Since IME Davis backs up his "opinions" with empirical evidence and physics, I'm wondering if you could do the same?
    #11
  12. DAKEZ

    DAKEZ Long timer

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    That guy spews :topes He is right that the tire will last longer. (if you can manage to keep them from washing out and faceplanting you to your death) But it comes at a cost of poor handling and a jolting ride.


    Motorcycle tires are made (need to) to flex to provide a proper contact patch and operating temperature. This is especially important while turning.

    If all you do is drone down the interstates then go ahead and run higher pressures. If you like the back roads and twisties then go with less (what is recommended for the BIKE)

    This is the way to go.

    #12
  13. LuciferMutt

    LuciferMutt Rides slow bike slow

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    Suddenly all the topics in faceplant make sense when people randomly slide out on nothing during slow turns. Running your tires at the max PSI on the sidewall is eating up half the traction you'd have otherwise...
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  14. DAKEZ

    DAKEZ Long timer

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    :photog
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  15. randyo

    randyo Long timer

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    the pressure on the sidewwall is NOT the maximum pressure for the tire, it is the pressure at which the tire acheives its maximum weight load

    for instance the Karoo T's on my V-strom read "Max Load 716 lbs @ 33psi" go to the Metzler website and they recommend running 38psi F and 42psi R on a V-strom well over the 33psi on the tire

    once I questioned Avon why they recommended higher pressures than Suzuki did on my SV650, in their e-mail to me, they answered that it was due to their VBD carcass design AND that for every 2psi under their reccomendation, expect 10% loss in treadlife with no significant increase in traction

    E-mail the tire manufacturer ask THEM what you should be running for your bike and your weight

    high pressure is NOT a safety issue, airing down for off road is a placebo
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  16. randyo

    randyo Long timer

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    bs
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  17. LuciferMutt

    LuciferMutt Rides slow bike slow

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    hyperbole

    note: that isn't pronounced with a "bowl" on the end.
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  18. rivercreep

    rivercreep Banned

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    http://www.motorcycleanchor.com/motorcycle/how_to/mc_tires.html

    Always keep in mind that what's written on your bikes swingarm for tire pressure is a suggested parameter to be used with stock size tires.
    One of the many reasons WHY is because the suspension is designed to work in conjunction with the flexability of the tires sidewall. Upping pressure is almost like increasing spring rate (to an extent) and vice versa. An example would be when NASCAR teams adjust their tires pressure a measely 1/2 psi or more and it helps fine-tune their suspensions reactions.
    What works best for 1 bike/rider combo might not work for another guy who's 1/2 the weight on virtually identical bikes.

    One observation I'm taking away from some of the comments here is a better understanding of why/how some people find themselves in positions where their tires delaminate or chunk. (and they always blame the tire mfg. when they themselves contributed to it)

    I'll never claim to be the sharpest tool in the shed but, sometimes after I log off this site, I feel like a freaking genius.:wink:
    #18
  19. antonac

    antonac Commuter

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    No need to run that low, I weigh 145 pounds and carry no cargo :nod

    Enlightening stuff, I guess it's not as cut and dry as I thought.
    #19
  20. Kommando

    Kommando Long timer

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    I use onroad pressures somewhere between what's recommended and the max on the sidewall. Any more almost always feels too hard and squirrely. Any softer typically generates a LOT of heat on the highway. I shoot for the 10% increase from cold to warmed-up.

    I know people who run the sidewall pressures in their cage. Then they wonder why their tires wear unevenly and the ride is crap. I typically run the cage tires midway between recommend and sidewall, but my GF and I corner hard, so MPG is better and wear is pretty even.
    #20