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

  1. #16
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    tar snakes to blame?

    a bit of an aside
    http://www.wristtwisters.com/forums/...kes-33652.html
    makes an interesting read.
    I have noticed that it seems the compounds used for tar snakes vary from area to area and have universally become slipperier over the past few years. Hwy 14 out of Cedar City, UT, was incredibly slippery when I took it in May 13, and that was with relatively new Pirelli Scorpion Trails at proper inflation. It became better over the crest on 14, but my psyche was wounded by then and all sphincters were shut and I had a death grip on the grips. This road was taken probably at about low to mid 70s (degrees, not mph).
    I guessed that the compounds used had changed, but the above article documents it and the wasteful and dangerous practice of using too much for the financial gain of the contractor.
    John

  2. #17
    Registered User helmut_head's Avatar
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    I've been underinflated.

    I guess I'll add a few lbs too and get better Obama fuel economy.....Good information from everyone, really!
    Helmut always wears a Helmet.

  3. #18
    Registered User georgej's Avatar
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    Thanks for all the replies.After reading,I wondered how i could be so far off.Under the seat on both my bikes the sticker states max 30 psi.The tire which is a Lazertec states a max of 42 psi.So I guess I will go with what it says on the tire.
    1978 R100RS Motorsport
    1978 R80/7
    1977 Triumph Bonneville
    1980 Honda XL500S

  4. #19
    Administrator 20774's Avatar
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    There's still some discussion that people like to have, but that 42psi is max cold inflation pressure. As a general rule, you probably don't want to ride at that pressure all the time. The ride will be rougher and you'll wear out the very center of the tire faster. Generally back off from that pressure. I know pressures are all over the map, but it seems that nominal pressures from what I've seen posted here and elsewhere would be 32 front and 36 rear. You can adjust from there due to feeling, handling, as well as with passengers or extra load when touring...maybe 1 psi higher in frong and 2-3 psi in the back.
    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!

  5. #20
    Registered User chewbacca's Avatar
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    Last weekend my RDC/TPS threw a warning at me. It said my front tire pressure was too low. I measured it and it was 36 psi. The ambient temp was in the upper 70's and I was hitting the twisties pretty hard so my guess is the actual tire temp was in the 80's. So NOW tell me what is the right tire pressure!?!? The RDC corrects the pressure to 20 degrees C or 68 degrees F. How many of you ride at a constant 68 degrees from start to return? Sunup to sundown. If you are riding in the 90's and pushing the turns, do you want the pressure pushing your sidewalls to be something corrected to normalized readings or what your digital pressure gauge says? I know what I do and have done for about 50 years. What do you do???
    Old But Not Dead
    Semper Fi

  6. #21
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    tire pressures on older Airheads

    My comments here are for ROAD tires (NOT off-road types or usage).

    Modern design tires require higher pressures than stated on the label under the seat on old Airheads, or in the Owners Booklet. Use the classic old pressures only with original type tires. The only "classic" tires you are likely to ever purchase are the Continental RB2 and K112. They give the Classic Ride; and handle well-enough, if you use the book values for TWO-UP and/or HIGH SPEEDS. Those pressures are way too low for modern tires. On all other tires I have ridden on, and there are a LOT of them, using such low values as higher twenties to lowest thirties will cause mushy unstable handling, with a feeling of the tire rolling sideways off the rim...

    Do NOT use the pressures printed on the tire as your standard pressure. Those are MAXIMUM designed pressures for the tire carcass.
    Modern tires may....or may not!....give the old rule-of-thumb of 6% pressure increase from riding awhile. The belted tires and stiffer sidewall types generally do not work so good in that regard...and measuring is critical anyway. The effect is more magnified with very hot asphalt in very hot Summer conditions, up to 10%, but NOT all makes/models of tires!

    As a fairly accurate general rule, if you ride solo, and weigh under 180 (or thereabouts), try 32 front and 36 rear as the absolute minimums, whether on a naked lighter BMW, or a heavier RT. The very BEST handling might be with 35 or 36 Front, and 40 Rear; but that is only for those that push rather hard into the twisties. I have found that 33F/38R is a very good compromise, most will like those pressures. Pressures are always measured with the tire cool....not right after riding...and NOT after heating up a lot from sunlight.

    If two-up, and/or you weigh considerably more, or you are doing higher-speed traveling, I suggest about 35 or even 36 front, and around 40 rear, or even a couple more pounds in the rear.

    All my comments on pressure values work well whether you are using metric sizes of, say, 90/90 or 100/90 front and 110 or 120 rear; or, inch sizes of, say, 3.25 or 3.50 front and 4.0 rear.

    NOTE that some tire manufacturer will give honest recommended pressures for their tires, and others will offer-up only what BMW might have specified, long ago. Some don't even offer any guidelines, except the maximum printed on the sidewalls. I can only speculate as to the reasons.
    There is an article at this URL, that discusses tires by brand and model, pressures, and lots more for your reading pleasure:
    http://bmwmotorcycletech.info/section5.htm


    BMW used to do extensive factory tire testing and made recommendations on tires, as well as pressures. I do not remember any tires for the early Airheads being tested and published by BMW since maybe the early or mid eighties.
    Certainly BMW has not published anything at all on tires/pressures since the mid-nineties, then only for the last Airheads, and were no changes. You MIGHT want to glance at the R100R type pressures, however.
    In MY opinion, all the Owners Booklets have the WRONG (too low) pressures for ALL models of BMW Airheads, up through 1985. EXCEPT if you have the Classic Tires. From 1986, the pressures were more accurate for real-world modern tires. Some brands and models of tires have been in production for a very long time. Almost none of the original Classic Ride type tires are now available, at least in the USA.
    snowbum
    MOA 17058

  7. #22
    Registered User georgej's Avatar
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    Thank you Snowbum for that reply to the thread. That helps me quite a bit. I ride about a half mile to a gas station to fill my tires.I even wait about 15 minutes for the tires to cool down just from that short ride.One question I have for you is.Do you consider new Metzler Lazertecs modern or classic tires?
    Thanks,again.
    George
    1978 R100RS Motorsport
    1978 R80/7
    1977 Triumph Bonneville
    1980 Honda XL500S

  8. #23
    Administrator 20774's Avatar
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    Quote Originally Posted by georgej View Post
    Do you consider new Metzler Lazertecs modern or classic tires?
    I'm not Snowbum, but if you go read his link, you'll see that he mentions the older Metzler tires, eg ME11, as more of the classic tire. Lazertecs IIRC are a more recent tire, thus probably not "classic" in this definition. That's the way I read it.
    Last edited by 20774; 10-13-2013 at 04:03 PM. Reason: Updated to reflect who is REALLY posting!
    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!

  9. #24
    Monza Blue 1974 R90/6
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    Quote Originally Posted by georgej View Post
    I ride about a half mile to a gas station to fill my tires.I even wait about 15 minutes for the tires to cool down just from that short ride.
    George
    Put this on your Christmas list and if Santa brings it, you'll have an extra 15 minutes to contemplate the days ride while having a cup of coffee!

    http://www.amazon.com/Schwinn-Steel-...1676615&sr=1-6

  10. #25
    #4869 DennisDarrow's Avatar
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    [QUOTE=20774;902599]Not Snowbum, QUOTE]

    So is this contributor "THE SNOWBUM" that we all love and cherish?..........If not.....What is to keep others from doing this and THEIR word taken as the gospel when it can actually be detrimental..............?????????............Than ks........God bless........Dennis

  11. #26
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    [QUOTE=DennisDarrow;902609]
    Quote Originally Posted by 20774 View Post
    Not Snowbum, QUOTE]

    So is this contributor "THE SNOWBUM" that we all love and cherish?..........If not.....What is to keep others from doing this and THEIR word taken as the gospel when it can actually be detrimental..............?????????............Than ks........God bless........Dennis
    Who takes Snowbum's word as Gospel?

  12. #27
    Administrator 20774's Avatar
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    [QUOTE=DennisDarrow;902609]
    Quote Originally Posted by 20774 View Post
    Not Snowbum, QUOTE]

    So is this contributor "THE SNOWBUM" that we all love and cherish?..........If not.....What is to keep others from doing this and THEIR word taken as the gospel when it can actually be detrimental..............?????????............Than ks........God bless........Dennis
    Dennis, I identified myself as NOT Snowbum but offered my take on the poster's question, even referred him to Snowbum's link and website. I'll go back and update my post to be quite clear...how's that??
    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!

  13. #28
    #4869 DennisDarrow's Avatar
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    Kurt.......ONCE AGAIN........thanks for what you and the other MODS do on here. That said, you know me and how I truly detest folks that run their mouth on here just to get thread count credibility; but NOW..............Some guy who plagarizes one of the true folks that one can go to in order to get a real and valid opinion as to what is going on with the mechanics of the "Airhead" design motorcyles. Seems that this fraud should be brought out and villified rather than just let it ride...........God bless.........Dennis

  14. #29
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    dennis- If you clik snowbum1's homepage, it's a direct link to Snowbum's articles. so what make you think S1 is not the real deal?

    also, all comments in this thread by S1 are consistent with comments contained in Snowbum's homepage.

    maybe before one calls for the vilification of a member and his/her postings, a bit of research would be appropriate?
    Ride Safe, Ride Lots

  15. #30
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    [QUOTE=jimmylee;902612]
    Quote Originally Posted by DennisDarrow View Post

    Who takes Snowbum's word as Gospel?
    many of us with extensive time on a BMW saddle count it as sage wisdom, if not an absolute guarantee of Holy Scripture.
    Ride Safe, Ride Lots

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