What is the best/correct tire pressure for the early Q's. The tires are Michelins Pilots 215/65R/15.
Thanks
Tire Pressure
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Mayhem_J30
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The recommended max PSI should be on the tire side wall. I wouldn't ever run that pressure unless auto crossing though. The recommended pressure from Infiniti is printed on the bottom side of your center console arm rest. That's only valid with OEM wheels of course.You'll get several different opinions here so the best might be to decide for yourself. Think about your driving habits and read up on tire pressures on http://www.tirerack.com .
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
The pressure on the tire placard is only for the oem supplied tire which is no longer available since the car has exceeded it useful SUPPORT LIFE of 7 years.
Notice that the TireRack had a close out on the 94-95-96 Oem tires a short time back so even those cars are now obsolete from a legal point of view!
When a tire is accepted for oem use it must be available for a certain number of years after the car is sold.
In 215/65/15 V RATED 29 psi cold is the minimum COLD pressure 44 PSI is the maximum COLD pressure.
A few tires in this size have a 36 psi max cold pressure again the 29 psi minimum applies.
Each tire model will have a different OPTIMUM pressure which must be determined by testing!
In theory the 95V rated [1521 pound max load capacity] tire has a 25% static safety factor [assuming 44 psi] when sitting still but under emergency braking the extra load slightly exceeds the rating of each FRONT tire even when filled to 44 psi so you are own your own!
Additionallly at 29 psi the tire is 100% utilized with 1002 pounds yet 1150 is the weight on each tire [driver and full tank of gasoline nothing else. This would translate to a required hot running pressure of 33.25 psi on a 44 psi max cold tire.
Roughly 1.0 more PSI cold all around per passenger and 1.0 extra psi on the rear for each 70 pounds of trunk loading.
Personally I would run 33 psi cold minimum all around and not be worried that it might expand to 37-38 psi hot after time on the highway.
Flex heat build up is what destroys tires but high flex is more comfortable.If you chose lower speed tires [H rated 130 mph max ] you might want to take the placard warning about extra pressure at speed to heart it says --- 35 psi cold above 129 mph on V rated [149 mph+] so 35 psi cold on H rated at 100 mph or 35 psi at 75 mph on T rated ..................
As tires age [mileage and months] the reserve goes down by 2 years or 30,000 miles depending on temperature much is gone!
Notice that the TireRack had a close out on the 94-95-96 Oem tires a short time back so even those cars are now obsolete from a legal point of view!
When a tire is accepted for oem use it must be available for a certain number of years after the car is sold.
In 215/65/15 V RATED 29 psi cold is the minimum COLD pressure 44 PSI is the maximum COLD pressure.
A few tires in this size have a 36 psi max cold pressure again the 29 psi minimum applies.
Each tire model will have a different OPTIMUM pressure which must be determined by testing!
In theory the 95V rated [1521 pound max load capacity] tire has a 25% static safety factor [assuming 44 psi] when sitting still but under emergency braking the extra load slightly exceeds the rating of each FRONT tire even when filled to 44 psi so you are own your own!
Additionallly at 29 psi the tire is 100% utilized with 1002 pounds yet 1150 is the weight on each tire [driver and full tank of gasoline nothing else. This would translate to a required hot running pressure of 33.25 psi on a 44 psi max cold tire.
Roughly 1.0 more PSI cold all around per passenger and 1.0 extra psi on the rear for each 70 pounds of trunk loading.
Personally I would run 33 psi cold minimum all around and not be worried that it might expand to 37-38 psi hot after time on the highway.
Flex heat build up is what destroys tires but high flex is more comfortable.If you chose lower speed tires [H rated 130 mph max ] you might want to take the placard warning about extra pressure at speed to heart it says --- 35 psi cold above 129 mph on V rated [149 mph+] so 35 psi cold on H rated at 100 mph or 35 psi at 75 mph on T rated ..................
As tires age [mileage and months] the reserve goes down by 2 years or 30,000 miles depending on temperature much is gone!
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maxnix
- Posts: 22627
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1995 Infiniti Q45t
2000 Infiniti Q45
Tire Pressures
Do search the archives for some very erudite remarks about tire pressures from Q45 tech and others.
Basically, you need to read the side of your tire. If they are not V or higher speed rated, with a load rating of at least 95, you could be in trouble. Only the Michelins Sport in H rating are acceptable lower speed rated tires, if speeds are suitably restrained.
The main point of the discussion is the maximum load rating is at a maximum pressure, usually 36, 44, or 50 psi cold . Your load carrying ability on that wheel is a percentage of your cold pressure to the maximum pressure to acheive the tires maximum load carrying capability. When calculated, your minimum resultant load carrying capacity should be 1250+ lbs. for each front tire and 1100+ lbs. for each rear tire on a non-a model. Extra passengers, speeds, and the a model will require commensurate increases beyond the minimum psi thus calculated.
Thus I would say Fred's (Palmerwmd) recommendation is right on for 95V rated tires with maximum load carrrying at 44 psi for around town and lightly loaded highway use.
Basically, you need to read the side of your tire. If they are not V or higher speed rated, with a load rating of at least 95, you could be in trouble. Only the Michelins Sport in H rating are acceptable lower speed rated tires, if speeds are suitably restrained.
The main point of the discussion is the maximum load rating is at a maximum pressure, usually 36, 44, or 50 psi cold . Your load carrying ability on that wheel is a percentage of your cold pressure to the maximum pressure to acheive the tires maximum load carrying capability. When calculated, your minimum resultant load carrying capacity should be 1250+ lbs. for each front tire and 1100+ lbs. for each rear tire on a non-a model. Extra passengers, speeds, and the a model will require commensurate increases beyond the minimum psi thus calculated.
Thus I would say Fred's (Palmerwmd) recommendation is right on for 95V rated tires with maximum load carrrying at 44 psi for around town and lightly loaded highway use.
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greg_atlanta
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
The DOT test only showed a +3 to -3% [dry/wet slip skid G's at 60 mph] variation in the 225/60/16 Goodyear LS tire when the inflation was changed from 35 psi to 24 psi as part of the research on tire monitor alarm but 17 psi was horrendous!
That test at least helps prove the theory on tire patch area not changing, the shape does but the wet test was less than accurate and they admitted it.....need another Million dollars to proceed .
That test at least helps prove the theory on tire patch area not changing, the shape does but the wet test was less than accurate and they admitted it.....need another Million dollars to proceed .
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maxnix
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1995 Infiniti Q45t
2000 Infiniti Q45
Yoko AVS dB
And I run 38 psi front, 35 psi rear for general use on the same tire as Greg in Atlanta.
I find the extra pressure, besides increasing load carrying capacity, provides a quicker response and resistance to hydroplaning. Ride comfort is still high, and the tire is better protected when those sharp pavement irregularities are impacted.
I find the extra pressure, besides increasing load carrying capacity, provides a quicker response and resistance to hydroplaning. Ride comfort is still high, and the tire is better protected when those sharp pavement irregularities are impacted.
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
http://www.tireindustry.org/go....html
I'm in the process of reading all 5403 comments something like 100,000 pages.
But GEMS of wisdom keep popping up like a comment by Ford that the reason they use such low OEM tread wears is they feel that after 2-3 years of sitting as a full size spare that a tire may not meet their specs when placed on the road to replace a blown out one. Primarily from oxygenated damage and heat cycling in the trunk.......FORD wants tires tested at 105% of max load and agrees that 85% max load on the vehicle is much more suitable vs the current 88% say the 3% would probably significantly reduce failures.
See why I keep recommending that owners find tires that have a HIGHER LOAD RATING than oem!!!!!!!!!!!!!!!!!!!!
The NHTSA site uses TIFF or PDF format so I can't easily copy {QUOTE} passages so knowing you won't read 100,000 pages you have to trust my paraphrasing or read some of the summary pages I find as links.http://dms.dot.gov/search/docu...=8011
http://www.detnews.com/2002/au...4.htm"But the industry is more alarmed at the public perception that would be created by tire failure rates as high as 54 percent. " .....under the new test proceedure
I'm in the process of reading all 5403 comments something like 100,000 pages.
But GEMS of wisdom keep popping up like a comment by Ford that the reason they use such low OEM tread wears is they feel that after 2-3 years of sitting as a full size spare that a tire may not meet their specs when placed on the road to replace a blown out one. Primarily from oxygenated damage and heat cycling in the trunk.......FORD wants tires tested at 105% of max load and agrees that 85% max load on the vehicle is much more suitable vs the current 88% say the 3% would probably significantly reduce failures.
See why I keep recommending that owners find tires that have a HIGHER LOAD RATING than oem!!!!!!!!!!!!!!!!!!!!
The NHTSA site uses TIFF or PDF format so I can't easily copy {QUOTE} passages so knowing you won't read 100,000 pages you have to trust my paraphrasing or read some of the summary pages I find as links.http://dms.dot.gov/search/docu...=8011
http://www.detnews.com/2002/au...4.htm"But the industry is more alarmed at the public perception that would be created by tire failure rates as high as 54 percent. " .....under the new test proceedure
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Q45tech
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1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
http://216.239.51.100/search?q...UTF-8Well they finally settled on Titanium out riggers to keep the tested SUV from rolling over vs the $25,000 Carbon Fiber outriggers.
http://www.rolloverlawyer.com/MonteroRo ... Runge1.htm
http://www.rolloverlawyer.com/MonteroRo ... Runge1.htm