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Old 03-21-2012, 06:52 AM   #1
antonac OP
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Running tires at the sidewall max PSI

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.

Quote:
Stamped on the outside of many of your tires is a recommended tire pressure range. (At least an upper limit.) For longest tire life it is my recommendation that you strive to keep them at the higher limit of those recommendations (regardless of what your motorcycle owner's manual might say to the contrary.) Further, this pressure should be determined while the tires are cold - meaning, have not been used for a couple of hours.
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?
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Old 03-21-2012, 07:01 AM   #2
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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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Old 03-21-2012, 07:15 AM   #3
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Quote:
Originally Posted by antonac View Post
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?


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.
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Old 03-21-2012, 07:16 AM   #4
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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.
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Old 03-21-2012, 07:28 AM   #5
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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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Old 03-21-2012, 07:34 AM   #6
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Originally Posted by duck View Post
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?

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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Old 03-21-2012, 07:45 AM   #7
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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,
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Old 03-21-2012, 08:42 AM   #8
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Quote:
Originally Posted by duck View Post
Despite the URL that site is mostly the OPINIONS of one guy. He posts many controversial things there. (i.e. bullshit)
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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Old 03-21-2012, 08:50 AM   #9
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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.
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Old 03-21-2012, 09:30 AM   #10
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Quote:
Originally Posted by antonac View Post
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. ?
Odd statement when the sticker on my KLR says 21psi.
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Old 03-21-2012, 09:33 AM   #11
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Quote:
Originally Posted by duck View Post
Despite the URL that site is mostly the OPINIONS of one guy. He posts many controversial things there. (i.e. bullshit)
Hmmm. Since IME Davis backs up his "opinions" with empirical evidence and physics, I'm wondering if you could do the same?
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Old 03-21-2012, 10:23 AM   #12
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Quote:
Originally Posted by duck View Post
Despite the URL that site is mostly the OPINIONS of one guy. He posts many controversial things there. (i.e. bullshit)



That guy spews 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.

Quote:
Originally Posted by Bill Harris View Post
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 it's 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.
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DAKEZ screwed with this post 03-21-2012 at 11:34 AM
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Old 03-21-2012, 11:05 AM   #13
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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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Old 03-21-2012, 11:31 AM   #14
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Old 03-21-2012, 02:11 PM   #15
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Quote:
Originally Posted by antonac View Post
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?
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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