optimum tire pressure for best MPG?

My tires are inflated to the recommended PSI based on the sticker slapped on my NB. What pressures are the high mileage champs using?

I'm running 38psi front and 35psi rear on my 225/50/16 tires.

I'm running 34 PSI all around on the original Michelin MXV4s ad have 51.6 MPG lifetime average at 36K miles - 5 speed of course.

I've not tried for any type of fuel economy championship, above is what I've got ussing the car in a fairly docile manner - 75 on the interstate, <= 10 over the limit most everywhere else!

For the record, I'm running 29 PSI front/28 PSI rear on my Goodyear 205/55R/16's... per the factory sticker. Looks like I ought to increase that a bit....

Drive around for a bit and put your hand on the tread. Is the center of the tread warmer than the edges? take some air out. Is the edge warmer than the center? etc., etc., etc.

If you don't understand, search for one of my old posts.

Originally posted by Tapokata:
My tires are inflated to the recommended PSI based on the sticker slapped on my NB. What pressures are the high mileage champs using?

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<font size="2" face="Verdana, Helvetica, sans-serif">40 psi all around, a bit stiff but best for mpg . . .

Bob

I run 35 all round, and over 100k miles, have averaged 59.8 mpg imp. I dont rotate and have worn out one set of rears and the second set of
fronts will last another 4 or 5k.

The dealer inflates the tires to 30 psi, but when I get the car back first thing is I do is to get them to 36psi on all five of them.

John

Around town for softer ride I run 38 PSI F&R when I travel I run 40 PSI F&R. Have 51,000 on NB with orignal MXV4 205/55/16's. Max inflation for car loaded to max is 44 PSI. I have perfect tread wear streight across the tire and expect to go to 70+ thousand miles on them.

Saw a NB TDI with 57K on it last week and the tires were normally kept at (I asked) 35 PSI were wore out and would not pass a safety inspection. Most of wear was on the edges (inner & outer) of the tires, they were bald with some tread in the center of tire. Person was amazed at my tires (same brand) and that they would be in better shape at 77K then her's were at 57K. At $150+ for tires for the car I want them to last as long as possible.

You have to be careful to the maximum inflation that the tire manufacturer states on the tire's sidewall.

Working part time in a gas station, I've seen this senario a lot: people telling other people how much to put in their tires without looking on the sidewall at first.

If it's written, it's because you have to read it!!! It ain't written for the blinds as I would say.

If it says that the maximum inflation is 35 psi and you put 40 psi in them, well, your tires could very well fail on the highway, something you don't want to happen.

My mother's TDI 4 seasons (Michelins, don't know what kind) are rated to a max of 35 psi. Her winter tires (Bridestone Blizzak) are rated to 44 psi.

In a recent trip (2000 km, 1240 miles) I've put 28 psi when the tires were cold.
After a few hours of drive I've checked them and they were at 34 psi (the max pressure on the sidewall is 35 psi).

So, if you apply the same method of inflation to a tire with a max pressure of 44 psi indicated on the sidewall, you would put around 37-38 psi when they are cold.

You'll have to experiment and note which pressure is best to put when the tires are cold.

My guess is that if you exceed the max pressure indicated on the sidewall of the tire when they are hot, you'll have more chances to blow a black donut.

Rammstein.

[ September 21, 2002, 22:14: Message edited by: Rammstein ]

Originally posted by Old Navy:
At $150+ for tires for the car I want them to last as long as possible.

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Try the Tire Rack.

Michelin Energy MXV4 Plus in size 205/55-16 are on special now for only $116.

Better yet, go to the Bridgestone Potenza RE950s for only $94 each, and you get an extra 32nd of an inch of tread depth (11/32 vs 10/32 for the Michelins!) and the Bridgestones are a better rated tire in every respect.

Originally posted by Rammstein:
You have to be careful to the maximum inflation that the tire manufacturer states on the tire's sidewall.

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<font size="2" face="Verdana, Helvetica, sans-serif">Good point, but max pressure noted on the sidewall of my stock Goodyear's RSA's is 51 PSI - so running them up to 38 or 40 ain't gonna cause them to blow....

I took 'em up to 38 today, and will follow RiceEater's method- although given that the temperature feeling in my hands has been shot for 20 years, I'll borrow the thermal gun from the shop and measure across the tires and inflate/delfate by trial and error. In any case, it sounds like the factory recommendation of 29 psi is a tad bit low...

Michelin recommend that the energy tyres are inflated 3 psi above the vehicles recommended pressure to begin with, anyway, (at least for running to the speed a tdi is capable of)
Check the tyre manufacturers data sheet.

You'll never go too far wrong by simply inflating tyres to the vehicle manufacturer's "full load" figures for normal everyday use. If you find that scenario uncomfortable and are seldom fully-loaded, revert to the normal figures.

It's naive to seek to obtain maximum mileage out of tyres by adjusting pressures upwards to above the full-load pressures for that reason alone. Manufacturers' figures consider the variety of road & weather conditions to be encountered. Having excessively over-inflated tyres in slippery conditions (rain, snow) is just plain stupid, as grip diminishes.

Do you remove the rear seats & all the trim to improve fuel economy? Do you remap the ECU to produce the absolute max fuel ECONOMY to the detriment of acceleration?

Better to be safe than stupid.....

- Richard

Hmm. Max load (cold) pressure is 32 psi front; 38 psi rear. Bled the fronts down by six pounds. I'll see what the temp variation is with the thermal gun...

I don't think VW ever considered that you would run a tire with a max pressure of 51psi. Therefore applying their suggestions to that type of tire will be low.

Personally, if I was running those tires, I would put in about 45psi cold and see how they felt for a while.

Tapokata, you'll have to experiment.

I would start in the low 40's and go up in pressure to achieve around 50-51 psi when the tires are hot.

The thermal gun is a good idea, but if you don't have one handy, a tire gage is less expensive and probably easy to use.

Weedeater, I would think that VW puts the same “tire pressure” stickers for most TDI (maybe not on NB running 16 inch) and following what the tire manufacturer recommends is preferable.

28 or 32 psi is probably recommended for a tire with a max pressure of 35 psi.

I'm sure that VW doesn't change the sticker every time it changes tire supplier, so going with the sidewall max pressure would be the finest way to get the best out of your tires.

Rammstein.

[ September 23, 2002, 03:08: Message edited by: Rammstein ]

Well, 38 psi rear (without a heavy payload) may be a tad too much. Took it out on the freeway a couple of hours ago, the ride a bit smoother than running all four @ 38 psi.

However, when I had to jump on the brakes at 65 mph to politely allow Mr. and Mrs. Knucklehead to cut me off as they headed for an off-ramp, the rear end decided it was going to come a bit left, in an attempt to prove that the NB is as equally un-aerodynamic going backwards as forwards It was sort of like my old '65 Mustang used to do in the rain.

These are the OEM Goodyear Eagle RS-A's, not the Michelin's. We're a month or so away from the rainy season here- probably better to have found this bit of handling trickery out now on dry pavement. The MPG and tire life become infinite when the car is on it's roof and all four wheels are in the air

I'll wait for things to cool off a bit, and step the pressure down closer to the 32 psi front.

I went to 38 psi all around recently. I have filled up 3 times, with each fill-up between 10 and 12 gallons of Amoco #2. My fuel economy has steadily increased from 39 mpg to 42 mpg.

Although not scientific per sé, I feel as if the increase in tire pressure may have contributed to my increase in fuel economy.

OBTW, my car has 25,000 miles on it... original everything, including the tires- Continentals, made in Germany.

Shawn