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Author Topic: Tire pressures on Z rated tires  (Read 3675 times)
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Richard Thomason
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« on: February 25, 2011, 03:27:39 PM »

I just bought a new street car with Michelin Pilot Sport PS2 F-P255/40ZR19 and R-P285/35ZR19 tires. How much pressure are guys using at speed (140, 160 180 200)? Manufacturers rec. is 32#, max press rating is 51#. I'd hate to suck the beads in at some fun speeds. Only closed course I assure you.
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Cajun Kid
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« Reply #1 on: February 25, 2011, 05:17:32 PM »

Richard, both my Benz's have Michelin tires and the cars manual and door stickers  on both say 32 PSI..max

Keep in mind the PSI on the car door is from the car manufacturer NOT the TIRE COMPANY... The car company also wants a nice comfy and quite ride..

Remember a few years back when all the Ford Explorers got bad press for rollovers due to tire failure,, that was Fords tire pressure at 32psi,,, at 40psi those tires would not have reacted the same way,,, so I always go by what the TIRE says not the sticker on the car door.

Most performance street legal tires like that will work great at 80 to 90 % of the tires max PSI.. I never run 28/32 like my car sticker says,,, I run 40 year round... 

and for High speed driving I would bump to 45psi (just stay at or under the tires max psi)

Have fun and be safe

Charles
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DocBeech
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« Reply #2 on: February 25, 2011, 07:32:07 PM »

Hmm I am the opposite of him. I run Michelin Pilot Sport A/S Plus 245/40 18 front and rear. The Racing PSI I run is 28-30 depending on what the days temps will be. My tires will heat upto about 32-33 PSI if they are run cold at 28 PSI. You can count for a 4 - 5 degree temp change after the tires are hot. I have never had an issue and I run 170+ on the track.
« Last Edit: February 25, 2011, 10:34:02 PM by DocBeech » Logged
Stan Back
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« Reply #3 on: February 25, 2011, 07:51:38 PM »

They won't gain as much temp at higher pressure.
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« Reply #4 on: February 25, 2011, 10:42:54 PM »

Why not run nitrogen?
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« Reply #5 on: February 26, 2011, 12:56:52 PM »

Thanks for your info guys. I'm not as worried about heat buildup as I am sucking the beads off due to centrifigal force from the high rpms. I guess it will be a tradeoff for ride vs. safety. I was kind of thinking of running 40-42 pounds. Just wondered what you guys run on the airport strips.
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« Reply #6 on: February 26, 2011, 04:22:44 PM »

I run 42 psi on my Z Rated tires at Maxton and Loring... I turn over 8000 rpms...

I think going below 40psi  is not a good idea for high speeds.

Charles
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DocBeech
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« Reply #7 on: February 26, 2011, 06:53:00 PM »

I run 10,500 RPM at 34-35PSI(On a Hot Tire).
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Stainless1
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« Reply #8 on: February 26, 2011, 07:28:36 PM »

I run 42 psi on my Z Rated tires at Maxton and Loring... I turn over 8000 rpms...

I think going below 40psi  is not a good idea for high speeds.

Charles

I run 10,500 RPM at 34-35PSI(On a Hot Tire).

You guys must be going really fast.... 8000 rpm tire speed is about 550 MPH on a 23 inch tall tire...  shocked  shocked
 cheers
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« Reply #9 on: February 26, 2011, 09:04:24 PM »

IMHO, I think a clarification may be necessary. If you are running a tall sidewall on a V rated tire, like a Firestone PV41,  high pressure is not a problem and might actually help by providing a lower rolling resistance. If you are running a short sidewall V rated tire, like a 45 or 50 series, you will probably experience some scary handling at higher speeds. These low profile tires were designed to handle the best at high speeds, at the pressure indicated on the sidewall and not at the rock hard pressures that we have been used to in the past with tall sidewalled tires. I have experienced this scary handling on my 50 series tires when I first ran them at higher pressures and when the pressures were returned to 35psi, the handling returned. Whether or not the bead will be sucked away from the rim, remains to be seen.
IMHO,
Peter   
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Peter
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salt27
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« Reply #10 on: March 02, 2011, 12:48:50 AM »

I just bought a new street car with Michelin Pilot Sport PS2 F-P255/40ZR19 and R-P285/35ZR19 tires. How much pressure are guys using at speed (140, 160 180 200)? Manufacturers rec. is 32#, max press rating is 51#. I'd hate to suck the beads in at some fun speeds. Only closed course I assure you.
Did you buy yourself a B-day present?
What kind of car?
Happy Birthday Richard.

Don
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racergeo
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« Reply #11 on: March 02, 2011, 01:18:53 AM »

  MY guess, Z06 Corvette HuhHuh
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ol38y
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« Reply #12 on: March 02, 2011, 11:21:18 AM »

Hmm I am the opposite of him. I run Michelin Pilot Sport A/S Plus 245/40 18 front and rear. The Racing PSI I run is 28-30 depending on what the days temps will be. My tires will heat upto about 32-33 PSI if they are run cold at 28 PSI. You can count for a 4 - 5 degree temp change after the tires are hot. I have never had an issue and I run 170+ on the track.

When I was racing vintage flat track, motorcycles, I was told if the tire pressure gained 2lbs from cold to hot, you had the right tire pressure. The tires won't get as hot on dirt as pavement so IMHO it sounds like you've found the right pressure...
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Larry Cason
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Richard Thomason
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« Reply #13 on: March 04, 2011, 01:54:50 PM »

Just a grandfather's car. Cadillac CTS-V coupe.
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salt27
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« Reply #14 on: March 04, 2011, 02:07:27 PM »

Nice, but it's not what my grandfather drove [he took the bus]. grin

Don
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