tire pressure

2003 vw gli michelin HX MXM4 225x45x17
I can't find the listing for tire pressure. It's not at the door jamb. Not in the users manual. I called service and he said 32 in
all four.
I'm taking a 2,000 mile highway trip next weekend, at about 70 or hopefully 80mph. Any recommendations for tire pressure appreciated.
Sam
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What is the max pressure rating on the tires? How loaded will you have the car?
Without those answers, a good ballpark is to run them within about 10% of max pressure.
If max is 44psi, run them about 40, unless you have the car loaded down, then run them higher obviusly not going above max pressure.
Unless you are still on the original, or buy OEM tires when you replace them, the tire pressures given by the manufacturer are useless. You need to go by the tires pressures, not the car...
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Agreed. When in doubt (lacking OEM VW information), keeping them higher rather than lower is better.

to
I'm going to somewhat disagree on that one.
If you buy the same size tires as original (can be a different brand) and especially if the load index is the same, use the manufacturer's recommended pressure.
If you vary from the OEM size or load rating, then yes...you'll probably need to use different pressures.
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Biz wrote:

This is only a max for the tires and is wrong for most cars.

Wrong!!!!
That max on the tire only tells you that going higher may blow out the tire and has NOTHING to do with what is correct for the car. Different cars and tire sizes on a car call for different pressures. If the pressure called for by the manufacturer is higher than that printed on the tyre, it only means that the tire can not safely be used on that car.
http://www.drivers.com/article/354 /
Sorry, but the tire-rack use to have a list of correct tire pressures but it seems it is no longer available.
Stick with what the dealer told you.
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Joseph E. Meehan

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I go with Joseph. Start by looking at the door to the fuel cap. That is where it is on my car. The tire is made to fit many cars. The maximum pressure is for the maximum load. 1356 lbs at 44 psi. 4 tires could hold up 5424 lbs. I don't think my Jetta wagon GVWR is that high, actually my GVWR is 4211which is about 77% of what the tires are rated for at maximum pressure. Doing some math which could be faulty the maximum load the car can handle would put the pressure at about 34 psi. This assumes some linear relationship between max pressure and load rating and that the car is perfectly balance for and aft.

Jim B.
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Guys, you're missing a valid point that apparently youdidnt get from my post. I have an 1985 GTI, it came with tires that had a max pressure of 32 psi, so recommended was around 26-28 depending on front or rear. All the performance tires today are 44 psi tires, you would not be wise to run those tires at 26-28 lbs. you can disagree all you want, but I talk to tire engineers all the time. I get great traction, great wear, and great mileage running the tires around 42 all the time. To each his own, but I know this works and is approved by the tire manufacturers.
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Biz wrote:

The pressure on the tire sidewall does NOT mean a thing about what pressure you should use other than you can't use that tire on a car that would call for a higher pressure than that.
If you have not changed the size of the tire, then the proper pressure has not changed!
Now there may be some question about what the proper pressure really should be. Your starting point should always be their recommended pressure from the manufacture of the car of that size tire on your car. You normally will see two recommendations, one for light load and one for heavy load. Many people like to increase the recommended pressure a few pounds. I try to keep mine between those two numbers.
Always check your gauge, as many are off by as much as five pounds.
REPEAT - THE PRESSURE ON THE SIDEWALL OF THE TIRE DOES NOT INDICATE THE PROPER PRESSURE FOR YOUR CAR!!!
Tire manufactures may make recommendations for proper pressure, but it can not be placed on the tires as the tires fit many different cars each calling for different pressures. They may provide that information in other forms, but it must be given for each car, not tire.
If your tire engineer is saying anything else, he needs to go back to school!
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Joseph E. Meehan

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To the guys that said 'look behind the gas filler door', thanks. I thought I had seen some pressures listed, but I could not find it in the owners manual.
1/2 load full load F R F R <100mph 29 26 32 41 >100mph 33 30 35 42
It's a little confusing that the rears get more pressure over 100mph.
I'm going to try your recomendation of 42 front and back. I don't know if this relatively low profile tire would wear out the center of the tread if it was overinflated or not. I think center wear is more common with bigger tires, such as oversized truck tires. I could be wrong. I hope the higher pressure protects the rims a little more, too, against impact damage from potholes (which I try to avoid).
Sam
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42 front and back partial load is silly. Read comments about load capacity at psi and weight of car. It is your car and you can do what you want but generally comfort, handling and tire life have an optimum pressure. Sometimes those three variables don to intersect at the same values but usually they are not way far away from each other.
Last time I read this debate a driving instructor from Road Atlanta weighed in with some comments. I don't think I saved his posts but he was not recommending this silly inflate to the maximum or close to the maximum for a variety of reasons. One is the handling gets messed up with overinflated tires. An overinflated tire will skip over bumps more than a properly inflated tire. Skipping about is a loss of traction which is not good in panic and threshold situations.
Here is one educated drivers observations> Note that the correct pressure for autocrossing is not the correct pressure for regular driving.
Quote
Sounds like some lawyers got involved somewhere. Let me explain.
Some years back, I used to autocross a Honda CRX on street tires. One of the things I was taught was to mark the tires with white shoe polish at the outside corners. Basically, you make a stripe from about 1 inch in on the tread surface, wrap around the edge of the tire, and end about 1 inch up the treadwall. Make a run, look at your marks, then adjust the tire pressure as needed. You where looking for a clean break right at the edge of the tread, which resulted in optimal grip. Running at street pressures typically scuffed the mark right on up the sidewall. Even with high performance 175/60-15 (running stock class) tires, I was running around 48PSI in the fronts and 40PSI in the rears. Every car there with a front weight bias, just like any modern water pumper VW, ran higher, NOT lower pressures in the front.
Lower pressures in the front cause the car to understeer when going into a corner too hot. In other words, the car tends to just plow on straight while you attempt to turn. Typically, this is considered safer than oversteering, for the inexperienced driver. Hence my lawyer comment. A properly setup front wheel drive car will tend to understeer if you keep your foot in the gas, although, it can be made to oversteer if you tap the brake, or if you have a manual transmission, quickly dump the throttle after turning in. You can adjust the balance/oversteer/understeer characteristics of your car by adjusting tire pressure.
Regardless of the what it says on the door jamb, your personal tire pressure settings may be different from what is suggested. If you find the corners/edges of the tread wearing quicker than the center, your tire pressure is too low. Likewise, if you are wearing the center quicker than the edges, your tire pressure is too high. Personal driving habits, how much load you carry, and how it is distributed, play a huge factor.
All that said, always keep your tires inflated above the minimum recommended pressure and below the max. Under inflation and excessive load are the WORST things you can do for your tires, and its not too good for fuel economy either.
The whole Ford/Firestone mess could have likely been avoided if owners had followed the numbers on the tire sidewall rather than what Ford posted on the door jamb. Fords numbers made for a softer ride, with lower handling limits, but allowed too much heat to build up in the tires.
BTW, I have a 1994 Passat now, and keep 38PSI in the fronts and 33PSI in the rears. It isn't much of an autocross monster, but I'm not afraid to let the tail get a little loose on occasion. ;-)
David Glos
end quote.
snipped-for-privacy@verizon.net (sheinrich) wrote:

Jim B.
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sheinrich wrote: ....

It often in not in the manual since they may change tires and if they use a different size tire, then the numbers need to be changed.
Glad you found the right numbers.

I suggest you consider following the recommended numbers. The front/rear difference is important for handling. Running 42 in the back should be fine, but overinflating the front could cause handling problems. My guess is the front could loose grip too early in a turn and you could end up with excessive understear in an emergency situation. I doubt if you would see it in normal driving.
Keep in mind they have developed those numbers with test, not guesses.
Note the full load recommendations assume you have additional weight in the back. If you don't, then you may want to consider that as well.
In any case good luck.
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Joseph E. Meehan

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Joesph, your link actually tends to back up my statements if you read the articles. Look, I'm not saying run the tires at max psi, I dont belevie I said that anywhere, but most people tend to run their tires underinflated, AND most vehicle manufacturers recommend lower tire pressures to give a "softer ride", especially in their suv lines. Has everyone forgotten the Ford Explorer/Firestone debacle already?
I'll pick on the Ford/Firestone fiasco, but its not uncommon at ANY of the tire companies...
Ford goes to Firestone and says heres the specs we want for a tire for our new SUV, Firestone designs the tire and gives recommended inflation pressures. Firestone thinks the ride is now too stiff, so they recommend lower pressures to the people that purchase the SUV's, and well, we all know the rest.
Liek I said b4, unless the tires are OEM or original, there is a good chance that the original tire pressures may not apply anymore.
YOu still go by the manufacturers recommendations, but its th e tire manufacturers recommendations that count, not the car manufacturers recoemmendations.
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Biz wrote:

You are not understanding what the link said.
"Under normal loads, inflate tires according to the vehicle manufacturer's recommendations"

It does if they are the same size!

Only if the tire manufacturer's recommendations are for your car. The correct pressure for that Ford Explorer is not the same for the same tire on a Ford Pinto.
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Joseph E. Meehan

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Is it behind the fuel door?
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Timothy J. Lee
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