best tire pressure for max mpg
Senior Member
Joined: Jul 2004
Posts: 252
Likes: 1
On our 20" runflats, came with 32s in front and 34s in rear. Ride is very comfortable for all passengers. I am amazed how smooth the ride is with the runflats. I was expecting them to be harsher based on all the reviews.
I agree increasing the rears to 38 will decrease the ride comfort and is not necessary for us since we're carrying small kids in the rear. I noticed different PSI recommendations in the fuel door depending on load.
The tire pressure monitor works well showing the individual PSIs. What's interesting is the pressure does not fluctuate too much (cold versus hot tires). At most +2 PSI when hot. I wonder if that's because of the stiffer runflats.
Does anyone know if the 4 TPMS sensors work in real time? If I let some air out, will it show the PSI immediately even if the car is not running?
I agree increasing the rears to 38 will decrease the ride comfort and is not necessary for us since we're carrying small kids in the rear. I noticed different PSI recommendations in the fuel door depending on load.
The tire pressure monitor works well showing the individual PSIs. What's interesting is the pressure does not fluctuate too much (cold versus hot tires). At most +2 PSI when hot. I wonder if that's because of the stiffer runflats.
Does anyone know if the 4 TPMS sensors work in real time? If I let some air out, will it show the PSI immediately even if the car is not running?
Last edited by dougpark714; Dec 31, 2010 at 07:10 PM.
Junior Member
Joined: Sep 2002
Posts: 62
Likes: 0
From: AZ
LS430, GL450, SL550
Although the runflats are a little noisy, I am pleasantly surprised that the noise level and ride quality are as good as they are.
I reduced the pressure in my rear tires this morning, and if I recall correctly the new pressures showed up immediately on the TPMS display. I did have to drive a little before the pressure warning displayed. I don't like reading manuals, but I had to do it to figure out how to reset the TPMS values.
I reduced the pressure in my rear tires this morning, and if I recall correctly the new pressures showed up immediately on the TPMS display. I did have to drive a little before the pressure warning displayed. I don't like reading manuals, but I had to do it to figure out how to reset the TPMS values.
Senior Member
Joined: Oct 2010
Posts: 302
Likes: 1
From: Sunny So-Cal
2011 QX56 (formerly '11 GL350)
I am now convinced this must be caused by defective front shock/bushing that we are still waiting for on parts from Germany. I'm hoping that perhaps we'll have the correct ride once they get all that squared away. (unless of course they buy my car back, which is what I'm hoping for. Still haven't heard back, but the case manager said he would not be back into the office until after Jan 5th.)
Senior Member
Joined: Oct 2010
Posts: 302
Likes: 1
From: Sunny So-Cal
2011 QX56 (formerly '11 GL350)
Oh yes, I can imagine. On our 04 H2, we went through a few sets of different tires, each time trying something different. I remember one time, he put on a very aggressive type tire (20" wheels) and boy could I feel the road. I never really complained about it but they were LOUDER than heck. You could hear me coming from a mile away. Never again. Even my current GL with all it's suspension problems does ride better than my H2. LOL (But I swear, my GL has more wind noise, as strange as that sounds!)
I hope you are enjoying yours! You still have snow?
I hope you are enjoying yours! You still have snow?
Super Member
Joined: Jul 2009
Posts: 814
Likes: 9
15 GL550
Tamz, I went on a three and a half hour trip in my 09 Bluetec through western Pennsylvania a couple days ago and I did a lot of driving around 60 MPH because of 50 and 55 MPH speed limits. There was almost no wind and not many cars or trucks on the road. I have to say that I found myself marveling at how quiet my GL was when no other cars were around. Literally there was no wind noise at that speed. The only noise was from the Goodyear tires and it was minor. Now when I drive in windy conditions I definitely hear more wind noise. You also hear a lot of noise coming from other vehicles when they pass.
Back on the whole tire pressure issue, I did few searches on the internet and found myself on the Goodyear and other websites. Nowhere could I find that your fuel economy could be improved any significant amount by increasing tire pressure above the car manufacturer's recommended pressure. The manufacturer's recommend pressure is based on a variety of factors one of which is the weight of the specific vehicle on which they will be installed. As stated in an earlier post, if you have too much pressure in your tires and not enough weight, your tires will wear heavily near the center of the treads. Along those same lines, you are reducing the overall contact patch of the tire on the road which has obvious implications. At best, over inflating your tires will give you extremely minor improvements in fuel economy at the expense of tread life, ride comfort, and in some cases stopping distance. This is not to say that some tires won't perform reasonably well at over inflated pressures. I just couldn't find any authoritative sources recommending it.
Back on the whole tire pressure issue, I did few searches on the internet and found myself on the Goodyear and other websites. Nowhere could I find that your fuel economy could be improved any significant amount by increasing tire pressure above the car manufacturer's recommended pressure. The manufacturer's recommend pressure is based on a variety of factors one of which is the weight of the specific vehicle on which they will be installed. As stated in an earlier post, if you have too much pressure in your tires and not enough weight, your tires will wear heavily near the center of the treads. Along those same lines, you are reducing the overall contact patch of the tire on the road which has obvious implications. At best, over inflating your tires will give you extremely minor improvements in fuel economy at the expense of tread life, ride comfort, and in some cases stopping distance. This is not to say that some tires won't perform reasonably well at over inflated pressures. I just couldn't find any authoritative sources recommending it.
Senior Member
Joined: Oct 2010
Posts: 302
Likes: 1
From: Sunny So-Cal
2011 QX56 (formerly '11 GL350)
Tamz, I went on a three and a half hour trip in my 09 Bluetec through western Pennsylvania a couple days ago and I did a lot of driving around 60 MPH because of 50 and 55 MPH speed limits. There was almost no wind and not many cars or trucks on the road. I have to say that I found myself marveling at how quiet my GL was when no other cars were around. Literally there was no wind noise at that speed. The only noise was from the Goodyear tires and it was minor. Now when I drive in windy conditions I definitely hear more wind noise. You also hear a lot of noise coming from other vehicles when they pass.
It gives me hope that when and if I get a new GL, I will at least be rid of the wind noise issue because it seems most everyone else has quiet vehicles. Leave it to me to pick this dang thing off the lot. Out of allllll the cars, I choose this one.
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Joined: Dec 2004
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taking off your horizontal roof racks will not only have some (doubtful?) effect on mpg, but will lessen significantly wind noise at speeds... that has been my experience after i took mine off (ahem... by forgetting to lower the truck when entering the garage and breaking both locks on both bars by hitting the house)
regarding tire pressure- i run my 19" now at 32/32 and have 15k miles on new tires wearing out nice and even
alex
regarding tire pressure- i run my 19" now at 32/32 and have 15k miles on new tires wearing out nice and even
alex
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Member
Joined: May 2008
Posts: 125
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From: Chicago
2007 GL450 2005 C55 2002 C32 sold 2001 ML320 sold
I run 40 psi all around on Pirelli Scorpion 19"s. I personally prefer the firmer ride it gives and cornering feels alot more direct than with the 32psi pressures that were recommended.
Only have 5000 miles on these, but no observable difference in wear pattern so far.
Only have 5000 miles on these, but no observable difference in wear pattern so far.
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Joined: Dec 2004
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Alex
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E55, GLS450, GL63, GLE350
