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Thread: Does tire pressure make that much of a difference?

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    Registered User georgej's Avatar
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    Does tire pressure make that much of a difference?

    I rode my RS down to Color in the Catskills Saturday.Before we left I put some air in the front tire,Metzler Lazertec.I usually run28-30 psi andthe crappy gauge at the station red around 33 or so.We were anxious to get going and off we went.On uneven pavement or those roadsnakes or almost any i perfection in the road the bike felt very unstable.I'm not a fast rider cruising along at 55-60 indicated.So can an overinflated tire,even by a few pounds make that much of a difference?
    1978 R100RS Motorsport
    1978 R80/7
    1977 Triumph Bonneville
    1980 Honda XL500S

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    33 front is not overinflated.

    on an airhead, I would wager that 34F/38R would be pretty close to ideal.

    what was your rear tire inflation?
    Ride Safe, Ride Lots

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    Administrator 20774's Avatar
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    How sure are you of the "crappy" reading of 33? Maybe it was closer to 36 or higher??
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    Registered User 88bmwjeff's Avatar
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    I don't trust gas station guages. I learned this early. As a kid, I would ride my bike into town, fill the tires up at a local gas station and go to a local store. Twice in about a month, both tires would be flat when I came out of the store. When I took out the tubes, they were blown--huge big holes that could not be patched. Since then, I carry my own tire pressure guage. My experiences have been that the station guages typically under estimate the pressure, which appears to be due to sliding guage portion getting bent by being dropped alot.
    Jeff in W.C.
    1988 R100 RT (the other woman)
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    My experience is that under inflation causes these handling problems. Under inflation causes a feeling of wandering, pushing wide on corners, sluggish response to steering inputs, etc. I have never knowingly ran my tires over inflated by more than 3 - 4 PSI. The only difference I could tell was it the bike road a little rougher.
    Roy G.
    85 K100RT Ol Ruby "Gone but not forgotten"

    02 K1200LTC Hoss

  6. #6
    Registered User georgej's Avatar
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    I'll have to check the pressure with my gauge.It seemed ok before I added air to the tire.The rear tire is at 30 psi.My friend suggested less stiff fork springs after he rode the bike for a half hour or so.
    1978 R100RS Motorsport
    1978 R80/7
    1977 Triumph Bonneville
    1980 Honda XL500S

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    Administrator 20774's Avatar
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    Rear tire pressure should be much higher than that. Probably around 36 psi...higher if carrying a another passenger or significant load. No higher than the sidewall cold inflation pressure, though.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    Pressures in the vicinity of 30 are great... if you're running the bike on the track. Too low for street usage, unless you really like getting about 60% of possible tire life.
    Ride Safe, Ride Lots

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    Quote Originally Posted by georgej View Post
    ... I usually run 28-30 psi ...
    I believe you have been running both tires with too low pressure. Don't know the specifics of your bike and your brand of tires, but usually m/c street tire pressures are in the neighborhood of 35-38 front and 40-44 rear. You have likely gotten used to riding around on low pressure tires and when you pumped them up a bit it felt strange and unstable to you. Buy yourself a gauge (most studies say any gauge is OK if you take care of it), then look at the max psi on the sidewall of your tires. Then check your bike's owner's manual--or Google it--for the recommended pressure. Start with the recommended psi, and you can go up a bit but not beyond the max psi shown on the tire.
    Royce
    On the coast of Kansas
    2012 F800ST

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    Quote Originally Posted by royce View Post
    I believe you have been running both tires with too low pressure. Don't know the specifics of your bike and your brand of tires, but usually m/c street tire pressures are in the neighborhood of 35-38 front and 40-44 rear. You have likely gotten used to riding around on low pressure tires and when you pumped them up a bit it felt strange and unstable to you. Buy yourself a gauge (most studies say any gauge is OK if you take care of it), then look at the max psi on the sidewall of your tires. Then check your bike's owner's manual--or Google it--for the recommended pressure. Start with the recommended psi, and you can go up a bit but not beyond the max psi shown on the tire.
    I changed both tires about 3 month's ago, and was really surprised because the new ride felt like something was wrong. When I "rolled" into a turn, I felt like I was going to fall over - it was too easy. I just found out that both my old tires must have had enough "flat" spot in the middle making it harder to roll the bike into a turn. With the new tires - WOW, they didn't have that flat spot in the middle. I agree, that below 30 psi is probably too low. I like mine up in the mid to high 30's. I never ride 2-up, but if I did, I would increase rear pressure to up around 40-ish.

    Best is to get a gage that you use constantly. Just maybe have your gage "gaged" with another to see where it stands in relation to another gage. Then when you find a pressure that works for you (within the limits described by other above), then use YOUR gage and no other to keep track of your own pressures, not the gages on the gas station air pumps.

  11. #11
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    38-40 PSI on almost all my Vintage and Classic bikes, 33-35 on the track bikes and 40 front and rear on the modern sport tourers.

  12. #12
    Aspiring Profligate jeff488's Avatar
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    Why not just run what the manufacturer recommends?
    '04 Silver R1150RT "Big Oel". '05 Yellow KLR 650
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    "I just want somewhere to ride and food when I get there."

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    Quote Originally Posted by jeff488 View Post
    Why not just run what the manufacturer recommends?
    With the older bikes, there have been substantial changes in tire construction since the bikes were produced. While the tire manufacturer information might be appropriate, and probably is, the bike manufacturer information is not. The best process is to stay under the rated (sidewall printed) maximum and find the correct pressure for the load by looking for a 2 psi increase from cold to hot. Some say a 10% increase, but I think that is better track guidance than street guidance. A rise of 5%, or more simply, 2 psi gives better tire life but still some warming of the tire.

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    Quote Originally Posted by jeff488 View Post
    Why not just run what the manufacturer recommends?
    Nothing specifically wrong with that, but you can find a "better" sweet spot by moving your tire pressure around a bit in increments. Different tires and different weights/loads and different riding techniques--all on the very same motorcycle--can respond differently and you might discover you prefer a different psi.
    Royce
    On the coast of Kansas
    2012 F800ST

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    Quote Originally Posted by royce View Post
    Nothing specifically wrong with that, but you can find a "better" sweet spot by moving your tire pressure around a bit in increments. Different tires and different weights/loads and different riding techniques--all on the very same motorcycle--can respond differently and you might discover you prefer a different psi.
    It is good to have a "benchmark" to start. Then, by keeping careful records and testing in exactly the same way each time, one can then formulate what are the best pressures to use.

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