Author Topic: Contentious topic? Tire pressure.  (Read 741 times)

Offline Toecutter

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Contentious topic? Tire pressure.
« on: May 16, 2018, 11:34:07 AM »
Hopefully not "type of oil" contentious...

So what's your personal preference... do you:

1) follow manufacturer's spec on pressure, no matter the tire.

2) go with tiree manufacturer's pressure

3) both be damned, pump 'em where you want.

Online Dilliw

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Re: Contentious topic? Tire pressure.
« Reply #1 on: May 16, 2018, 11:39:03 AM »
Hopefully not "type of oil" contentious...

So what's your personal preference... do you:

1) follow manufacturer's spec on pressure, no matter the tire.

2) go with tiree manufacturer's pressure

3) both be damned, pump 'em where you want.

4. Go with what you read on the Internet :)
George Westbury
Aiken, SC
2003 EVT "The Tank"
2011 Griso SE

L-824 and L-825


Online oldbike54

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Re: Contentious topic? Tire pressure.
« Reply #2 on: May 16, 2018, 11:58:14 AM »
Could be wrong but I believe the manufacturer(tire) just states max cold pressure, no recommendations.

 This right here  :1:

 The 10% always applies .

 Dusty
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Re: Contentious topic? Tire pressure.
« Reply #3 on: May 16, 2018, 11:59:21 AM »
Hopefully not "type of oil" contentious...

So what's your personal preference... do you:

1) follow manufacturer's spec on pressure, no matter the tire.

2) go with tiree manufacturer's pressure

3) both be damned, pump 'em where you want.

Like so many things in the world there is a procedure!
Briefly it is this:
Start where Guzzi recommends, probably 27psi front 30 rear.
Ride bike as you would normally would until tires are up to temp, 25-30 miles is plenty.
Hop off and check the tire pressure hot. It should be 10% higher. If itís more than 10% you are under inflated, if itís less than 10% you are over inflated.
If needed start process over the next day with slightly high/lower pressure as needed.
As a rule you want the front about 3 lbs lower.
Never exceed the manufacturer cold pressure.

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Offline Toecutter

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Re: Contentious topic? Tire pressure.
« Reply #4 on: May 16, 2018, 12:01:21 PM »
38 years of riding... and I have just now heard this 10% thing. Old habits are a hell of a thing.

Online Sasquatch Jim

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Re: Contentious topic? Tire pressure.
« Reply #5 on: May 16, 2018, 12:08:09 PM »
 I blow them up until my cheeks hurt and I get dizzy.
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Online pyoungbl

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Re: Contentious topic? Tire pressure.
« Reply #6 on: May 16, 2018, 12:08:43 PM »
38 years of riding... and I have just now heard this 10% thing. Old habits are a hell of a thing.

The 10% rule is an old racer's trick.

FWIW, my V7 manual says 36 front, 36 rear.
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Online Lannis

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Re: Contentious topic? Tire pressure.
« Reply #7 on: May 16, 2018, 12:10:37 PM »
Hopefully not "type of oil" contentious...


Probably won't be, mainly because two main variables that "run" oil threads are missing.

1) The parameters (as expressed clearly by the posters above) are pretty universal, the manufacturers always have recommendations, and the tire manufacturer has an upper limit.

2) Nobody can claim "I can't get the kind of air here within 2 minutes drive of the house that the tire manual recommends to put in, and they don't import it that grade of air into my country, so is it OK if I use pressurized cans of wasp spray to fill my tire?    There's a forum where everyone does it and they say it works great!"

So hopefully, this post will be IT!

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Online Bulldog9

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Re: Contentious topic? Tire pressure.
« Reply #8 on: May 16, 2018, 12:12:15 PM »
I used to always run 10% less than the max pressure on the sidewall, but after experimenting with different pressures,  I've settled on 34-36 front and 38 -40 rear on my Griso and Norge. This is from cold AKA sitting overnight.  Initially went 32 front 36 rear, but like the feel of the front end better with 34 or 36.

It's a matter of preference depending on the kind of feedback feel roll over that you want and of course your loads.

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Offline Toecutter

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Re: Contentious topic? Tire pressure.
« Reply #9 on: May 16, 2018, 12:13:57 PM »
Quote
so is it OK if I use pressurized cans of wasp spray to fill my tire?

They make WASP spray? Where can I get it, I'm constantly trying to get them to leave me alone... all those deck shoes and sweater vests...

Online Tusayan

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Re: Contentious topic? Tire pressure.
« Reply #10 on: May 16, 2018, 12:14:51 PM »
There is nothing IMHO you can do to make your riding safer than figure out which model tires work well on a given bike and maintain wear condition and inflation pressure so that it steers nicely.  The 10% rise thing is very likely correct to maximize life, but that is generally not the #1 goal for me.

depending on the weight of the bike and size tires, I find that 32 psig front and 36 psig rear is often a good place to start.  Then I adjust up to a few psi either way if needed to make the bike steer is a neutral way, neither falling in nor taking continuous inside bar pressure to hold a line.  If minor adjustments to pressure dont make the bike steer correctly assuming a reasonable chassis setup, the tires are either beyond their sell by mileage or a model/size mismatched to the bike.   Some bikes are a bit more fussy about tires than others. After a while you get a feel for it.

That is just my long term experience with sport bikes on the street.  YMMV depending on what you are doing with the bike.  Touring and racing may have different needs.   

Online SmithSwede

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Re: Contentious topic? Tire pressure.
« Reply #11 on: May 16, 2018, 12:16:34 PM »
If you want to get serious about tire pressure, don't inflate your tires with regular air.   Use radon gas instead. 

Then you can always just use a radon detector to find any leaks in your tires.
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Re: Contentious topic? Tire pressure.
« Reply #12 on: May 16, 2018, 12:17:24 PM »
I used to always run 10% less than the max pressure on the sidewall, but after experimenting with different pressures,  I've settled on 34-36 front and 38 -40 rear on my Griso and Norge. This is from cold AKA sitting overnight.  Initially went 32 front 36 rear, but like the feel of the front end better with 34 or 36.

It's a matter of preference depending on the kind of feedback feel roll over that you want and of course your loads.

 Interesting interpretation of the 10% rule  :huh:

 The 10% rule actually means that after completely warming up the tires , a 10% rise from cold pressure , IE 36PSI cold , right at 40 PSI warm is what you want .

 Dusty
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Online Dilliw

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Re: Contentious topic? Tire pressure.
« Reply #13 on: May 16, 2018, 12:22:27 PM »
Could be wrong but I believe the manufacturer(tire) just states max cold pressure, no recommendations.

Michelin had a tool on their website that was bike/tire specific but when I went to link it I see it's now gone.  Now they have the standard blurb about following the OEM recommendations and that their numbers are max cold only.

George Westbury
Aiken, SC
2003 EVT "The Tank"
2011 Griso SE

L-824 and L-825

Online Two Checks

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Re: Contentious topic? Tire pressure.
« Reply #14 on: May 16, 2018, 03:23:22 PM »
Synthetic or dino air?
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Online Kev m

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Re: Contentious topic? Tire pressure.
« Reply #15 on: May 16, 2018, 04:30:44 PM »
This right here  :1:

 The 10% always applies .

 Dusty
And the sidewall Max pressure doesn't apply UNLESS you're running max load or near it.
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Offline kingoffleece

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Re: Contentious topic? Tire pressure.
« Reply #16 on: May 16, 2018, 05:09:31 PM »
The Dunlop plant ( now Sumomoto or something like that) is right near.  The motoGP guys speak at our club meetings now and again.
They recommend the 10% rule for street tires.
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Online Kev m

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Re: Contentious topic? Tire pressure.
« Reply #17 on: May 16, 2018, 05:50:21 PM »

Let me clarify, yes it's a limit no matter the load but it's not SUPPOSED TO BE NEEDED unless you're near that load. It's the requirement for that load and less load means a lower ideal requirement.

Car links but same basic standards:

https://m.tirerack.com/tires/tiretech/techpage.jsp?techid=8

http://m.startribune.com/which-tire-pressure-rating-should-motorists-heed/296203951/
« Last Edit: May 16, 2018, 05:51:34 PM by Kev m »
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Offline pressureangle

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Re: Contentious topic? Tire pressure.
« Reply #18 on: May 16, 2018, 06:32:15 PM »
There are a couple different legitimate ways to determine pressure.

The stated sidewall pressure (in the U.S. anyway) is the pressure at which the tire can carry the stated load at a particular speed for an hour and remain within temperature parameters (I think it's 70mph but it's been a very long time since I researched)
The vehicle's manufacturer recommended pressures are for the tires that came originally fitted *only*. Of course, tires of equal capacity can be expected to perform similarly with those pressures; the recommended pressures are simply an opinion by the Mfg. of the best compromise between performance, mileage, and comfort.

Sport tires have two aspects, traction and durability; they are usually a direct trade-off. The only way to know that your tire pressure is correct is to know the manufacturer's recommendation for tread temperature, which you can only know by having a pyrometer and checking immediately after (or during, preferably-more difficult) the most severe usage. As an anecdote, when Metzeler gave us tires to run on 883 Sportsters at Daytona in about '96, we had to run down to about 12psi. *12psi* on a 460lb motorcycle running 135mph. Otherwise we just couldn't get them hot enough, and you'd think they were wiggly but that was not the case.

So somewhere between sidewall max and 12psi there is a sweet spot between max load, max durability, and max traction.

Good luck.
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Online Bulldog9

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Re: Contentious topic? Tire pressure.
« Reply #19 on: May 16, 2018, 07:06:35 PM »
Who said I was folowing a rule?  rules?? I dont need no stinking rules.........  :police:

Interesting interpretation of the 10% rule  :huh:

 The 10% rule actually means that after completely warming up the tires , a 10% rise from cold pressure , IE 36PSI cold , right at 40 PSI warm is what you want .

 Dusty
2007 GRiSO 1100
2016 Stornello #742
2017 MGX #265
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Offline wymple

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Re: Contentious topic? Tire pressure.
« Reply #20 on: May 16, 2018, 10:56:26 PM »
Touring or sport riding? An old BMW rider I knew ran his back tire never higher than 25 PSI. Any more than that and the tire rides a little high on the center and the edges don't do much to help support the bike. He rode double with his woman to all the lower 48, every province in Canada, plus Alaska. He got 20K out of his tires and had one flat in all that riding. He rode many hundreds of thousands of miles on his R90's. I have a hard time with the idea of getting under 35PSI, but as he said, when I change tires at 10-12K, they are always worn bad in the middle, the chicken strips look like new.
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