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Old June 24th, 2005, 19:18   #1
Nellie
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Default What is the proper tire inflation for new TDI?

Can anyone tell me what the proper tire pressure should be for my new '05 Jetta Wagon TDI? The sticker says 36 front 45 rear. The Conti tires say max 44 psi and the dealer recently adjusted all of them to 32 psi during the 5,000 mile service. Who's right?
Thanks,
Nellie
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Old June 24th, 2005, 19:37   #2
Ed's TDI
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Default What is the proper tire inflation for new TDI?

The ratings on the tire are just suggetions and the max is for whenever you pile a ton of cr@p in the trunk. If you rode around with 44psi in the rear, you'd find the ride pretty rough (although it isn't that bad when you're riding on 15" with a 65% aspect ratio!). For the best fuel economy, I found keeping the tires around 38psi was a good number. I ran the same tire pressure on my 17" Long Beach mags and still run 38psi with my 18" OZ's.

On a side note, I check the tire pressure each fillup and when I recently picked up a nail in the rear right tire, I noticed the ride was a bit off and it was because I noticed the varition in the tire pressure. The rear had dropped to about 26psi.
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Old June 24th, 2005, 21:03   #3
ruking
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Default What is the proper tire inflation for new TDI?

Quote:
Can anyone tell me what the proper tire pressure should be for my new '05 Jetta Wagon TDI? The sticker says 36 front 45 rear. The Conti tires say max 44 psi and the dealer recently adjusted all of them to 32 psi during the 5,000 mile service. Who's right?
Thanks,
Nellie
You see the obvious "range of pressure" PSI.

I have run 85% of the max sidewall pressure (37.4 psi) or between 38-36 front and 2#'s less in rear 36-34 (to balance out the tremendous understeer, a bit) Also much above 38 psi is a bit harsh riding to my SOTP experience. One caveat here of course is: I operate this TDI in reputedly the worst roads in the nation. So if one has buttery smooth roads, then a couple of extra psi might not be as harsh. However the same still applies as to the performance curve of the tire. Toward max psi you have to be a bit hypersensitive to the center of the tread wearing faster. Also shock absorption is less with much higher PSI.

This seems to be best pressure for the performance curve for the recommended tires. So far on GY LS-H's, I am pushing 56,000 miles and project between 100-130 k miles.
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Old June 24th, 2005, 21:35   #4
tjl
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Default What is the proper tire inflation for new TDI?

Quote:
Can anyone tell me what the proper tire pressure should be for my new '05 Jetta Wagon TDI? The sticker says 36 front 45 rear. The Conti tires say max 44 psi and the dealer recently adjusted all of them to 32 psi during the 5,000 mile service. Who's right?

The number on the tire is the maximum inflation pressure for the tire. Seems like the factory made an error, installing 44psi maximum tires on a car that it recommends 45psi in. Note that all pressures are measured cold, before driving.
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Old June 24th, 2005, 21:46   #5
whitedog
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Default Re: What is the proper tire inflation for new TDI?

Maybe the best pressure is the one that balances fuel economy with ride comfort without going out of bounds for what the tire states. If the tires are not original or the same as original, then it is best to go with what is on the tire.
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Old June 24th, 2005, 22:44   #6
burpod
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Default Re: What is the proper tire inflation for new TDI?

in my 05 i had 51 max psi tires (michelin energy mx4's). i run 43 front / 41 rear. but if they are 44 max psi, i would run 40/38.... but not higher. experiment. 38/36 would also be fine. i'm in the ~85% max pressure camp, with a couple extra lbs in the front
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Old June 25th, 2005, 16:22   #7
TornadoRed
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Default What is the proper tire inflation for new TDI?

I would start with Ruking's suggestion -- set to 85% of the max PSI printed on the tire's sidewall. I would not go higher, as this could lead to premature wear in the center of the tread. If the ride is too harsh for you, drop down incrementally. But 85% is a reasonable starting point for maximum fuel economy and even tread wear.
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Old June 25th, 2005, 16:30   #8
burpod
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Default What is the proper tire inflation for new TDI?

not too mention if there if you fill your tires up when it's 55 degrees, and then a few days later it's 80 degrees, your tires will be waaay over-inflated. this happened to me. i had them at 44 and a few days later in much warmer weather they were well at around 51-52lbs
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Old June 25th, 2005, 18:35   #9
nosootdzl
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Default Re: What is the proper tire inflation for new TDI?

PV/T gas law constant ...
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Old June 25th, 2005, 18:51   #10
Bob_Fout
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Default Re: What is the proper tire inflation for new TDI?

PV = nRT...aka the pervert law?
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Old June 26th, 2005, 07:33   #11
mailman
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Default Re: What is the proper tire inflation for new TDI?

The correct tire pressure is the pressure that will result in a maxium tire contact area with the road. This pressure will wear the tires evenly and provide the safest ride with maximum traction available for braking and turning. Fuel economy and ride "feel" should not be the criteria.

That being said, the correct tire pressure for your particular vehicle will vary with ambient temperature, vehicle weight, and tire make/model.

Best way to determine if you have the correct pressure is to use a method that was recommended by a friend of mine. You'll need a piece of your child's sidewalk chalk for this test. In a parking lot with the car in its "usual" driving conditions (i.e., load, temperature, etc.), draw a chalk line across the tread of your tires. Get back in the car and roll the car 10-20 feet (enough for a few complete tire revolutions) and check the chalk marks. If the marks show even wear, then your tires are properly inflated. Simple.

If the chalk marks show more wear in the center of the tread, then your pressure is too high. If the chalk marks show wear on the outside edges of the tread, then your pressure is too low.

Remember to thank your child for lending his/her chalk.
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Old June 26th, 2005, 13:42   #12
sootandclatter
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Default Re: What is the proper tire inflation for new TDI?

Self adjusting, pump them up till they go bang and you know its enough lol
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Old June 27th, 2005, 07:05   #13
tongsli
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Default Re: What is the proper tire inflation for new TDI?

I've never had a dealership or tire service place put my tires any higher than 34PSi.
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Old June 27th, 2005, 07:34   #14
dieseldorf
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Default What is the proper tire inflation for new TDI?

Quote:
Can anyone tell me what the proper tire pressure should be for my new '05 Jetta Wagon TDI? The sticker says 36 front 45 rear. The Conti tires say max 44 psi and the dealer recently adjusted all of them to 32 psi during the 5,000 mile service. Who's right?


Nellie, for some reason the cars sent to the USA are showing only the MAX inflation pressures. The cars sent to Canada have complete info. This discussion was recently covered over here: web page
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Old June 27th, 2005, 10:07   #15
tongsli
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Default Re: What is the proper tire inflation for new TDI?

Thanks DD,

I keep the front and rears and 32PSI. Most of the time, it's just two of us in the car.

L
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