Tire Pressure - VFR Discussion

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Tire Pressure I searched and found nothing this may be a repeat

#1 sigsauer33

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Posted 17 February 2008 - 09:41 PM

I was riding today and noticed that my ties felt like they were loving to hug the turns. I got home and check the tire pressure and realized that it was low. So I let the tires cool down for a few hours and re checked the pressure and still they were low. I normally run them at the Max PSI as stated on the rubber (42psi) my tires were at 35. Now granted I have no engineering degree but it king of makes sense to me that a lower pressured tire would tend to mold and hug more to the contour of the road.

Any input so that I dont kill myself in the future thinking that i know all!

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#2 slowf2337

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Posted 17 February 2008 - 09:51 PM

I usually run my PP's at 32-35 psi on the street. Less pressure allows for more flex in the rubber and lets the tire carcass heat up faster and maintain heat better. I do raise the pressure if I'm commuting though since it will wear faster with lower pressure. On the track when I used to run PP's I would start with 29f 28r psi cold and I got great wear and handling out of them but the pressure rise when hot got them up to 33psi hot. The Pirelli's I run now start at 27f 26r cold. The psi molded on the side of the tire is an inflation pressure when your operating at max load.

#3 Gap Trash

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Posted 17 February 2008 - 10:17 PM

I've been told that I'm somewhat anal about my tire pressure. I am known to adjust tire pressure quite often. I normally run about 34 on the street when I am riding some hard twisties. If I have to get out on the interstate BLAH, I run the highest pressure possible, usually about 42. I will run about 40-42 when commuting, but when it comes down to it I'm probably going to commute at whatever the last pressure in my tire was, just depends on the last thing that I was doing. If I am on the track I'm going to run 30-32, just depending on the conditions, ask around at the track and see what pressures others are running and what kind of feedback they are getting. BTW I keep a small analog gauge under my seat.

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#4 sigsauer33

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Posted 17 February 2008 - 10:30 PM

Some nice info here thanks a lot for the quick reply!

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#5 jeremy556

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Posted 17 February 2008 - 10:37 PM

Honda recommends 36/42 f/r, IIRC. In twisties I run 34/38 or so.

#6 MuddDawg

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Posted 17 February 2008 - 11:29 PM

jeremy556, on Feb 17 2008, 07:37 PM, said:

Honda recommends 36/42 f/r, IIRC. In twisties I run 34/38 or so.

My question is what does the Motorcycle manufacture know about whatever tire your running? Shouldn't you go by the tire manufacturer's recommendations since they designed the tire with whatever rubber compound?

#7 wera803

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Posted 18 February 2008 - 08:16 AM

MuddDawg, on Feb 17 2008, 11:29 PM, said:

jeremy556, on Feb 17 2008, 07:37 PM, said:

Honda recommends 36/42 f/r, IIRC. In twisties I run 34/38 or so.

They don't know. They recommend the pressures for the one or two tires they recommend for the bike. Of course how does a tire manufacturer know what bike you are puting the tires on either?? Should the pressures be the same for a Hayabusa and GSXR-600?? There is quite a bit of weight difference between the two.

I think it is just one of those things that you have to play with to see what works best for you, your bike, and your riding style.

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#8 jeremy556

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Posted 18 February 2008 - 09:51 AM

MuddDawg, on Feb 17 2008, 11:29 PM, said:

They don't, but the tire manuf. doesn't know what bike you are putting it on either and it's power, weight, etc.

I also don't know of many tire companies that give recommended pressures at all (except race tire distributors). The pressure listed on the sidewall is a maximum pressure, not a necessarily recommended one.

#9 spud786

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Posted 18 February 2008 - 11:03 AM

33psi cold is bout the lowest I run on the street on the front, that way I go blow through potholes and such without rim damage , any where around 40psi on the rear

#10 Monk

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Posted 24 May 2009 - 10:58 AM

wera803, on Feb 18 2008, 09:16 AM, said:

MuddDawg, on Feb 17 2008, 11:29 PM, said:

jeremy556, on Feb 17 2008, 07:37 PM, said:

Honda recommends 36/42 f/r, IIRC. In twisties I run 34/38 or so.

Take the cold tire pressure.

Ride the bike normally to heat up the tires...

Take the Hot Pressures of your tires.

You should be looking for a 5 % to 10% increase from cold to hot.

If you have more than 10% increase,,,, add air.

Example:40x5% is 2 pounds air ; 40x10% is 4 pounds air.

So if it reads 45 pounds of air. I need to add enough air ( how much ? ) to keep it under 10% increase ( 1 pound at a time,till I know what MY bikes cold tyre pressure is on a average temp. day ).

This is a tyre formula that was posted on here somewhere. Now I've been playing with it the last couple of days, and for it to work on my bike I've had to go up to 44lbs. on the rear cold to keep it under 10%(4 lbs.) when warm. The front tyre is right on at 36, and is only 38 warm(5%).
What I'm wondering is 42lbs. is suppose to be the max, but it runs cooler at 44 (according to formula). P.S. I weigh 230 lbs......
Has anyone worked with this "type of formula", and to what results?

I'm also 50/50 smooth to bumpy roads so I'm wondering about lack of tyre flex?

Anyone have any ideas? ..... Monk

This post has been edited by Monk: 24 May 2009 - 10:59 AM

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#11 Ryanme17

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Posted 24 May 2009 - 11:39 AM

Monk, on May 24 2009, 11:58 AM, said:

wera803, on Feb 18 2008, 09:16 AM, said:

MuddDawg, on Feb 17 2008, 11:29 PM, said:

jeremy556, on Feb 17 2008, 07:37 PM, said:

Honda recommends 36/42 f/r, IIRC. In twisties I run 34/38 or so.

What is bad about a 10% increase in tire pressure? A 3-4 pound increase in PSI is completely normal as the tire heats up. So what's the problem with that? If I'm running 34 psi I expect it to gain more than 3.4 psi as it warms up...

Also, although pressure does affect tire shape and contour, the main thing that affects traction is the heat of the tire. Hot tires grip better and wear quicker. Cold tires don't have as much grip but last longer. Lower pressures heat up quicker and stay hot through the twisties. Higher pressure tires might never get up to temp. Most people lower their tire pressures to run a track day or in the twisties. Obviously this is only affective to a point. If you're running only 20 psi your tire will handle worse than it will at 28 or 30 psi.

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#12 Monk

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Posted 24 May 2009 - 02:28 PM

Anyone have any ideas? ..... Monk
[/quote]

What is bad about a 10% increase in tire pressure? A 3-4 pound increase in PSI is completely normal as the tire heats up. So what's the problem with that? If I'm running 34 psi I expect it to gain more than 3.4 psi as it warms up...

Also, although pressure does affect tire shape and contour, the main thing that affects traction is the heat of the tire. Hot tires grip better and wear quicker. Cold tires don't have as much grip but last longer. Lower pressures heat up quicker and stay hot through the twisties. Higher pressure tires might never get up to temp. Most people lower their tire pressures to run a track day or in the twisties. Obviously this is only affective to a point. If you're running only 20 psi your tire will handle worse than it will at 28 or 30 psi.
[/quote]

I saw this formula and thought I'd try it. I took it out for a ride with the "quote/unquote" proper cold/hot settings today. As I said the front comes out ok with 36 cold.
The rear is much to hard/bouncey, so I'm going back to 42 cold.
The formula wasn't trying to stop the temp. from going up, it was just trying to put it in the correct range.
I was gaining 4.5 at 42 cold ( I'll just stay with it, I haven't had any problems at 42 cold).......... thx...... Monk