Best Tyre Presures

There has really been a lot of discussion here about tire pressures Jim. Most people, including myself, have discovered that higher pressures will definitely give you better mileage. I think the consensus here is to use 42/40 front/rear or 44/42 maintaining the 2 pound difference but just increasing the pressure. I use 44 pounds (the maximum on the sidewall) in all four and that works fine for me.

Try the search function for tire pressures or something like that and you will get more information than you wanted.

 

It's much better to pay attention to the values on the sidewall of the tire than those the auto manufaturer recommends. After all, they don't know the specs for whatever type of tire someone wants to put on, instead they play it safe by going with a lower number.

Not sure which tires you got, but there could be a number of reasons for the lower milage. First, the rolling resistance of the tire could be higher, which means it's a ltitle bit harder to rotate the tire when it's on the ground. The tire itself could be heavier. It takes much more energy to rotate a heavy object than a light one. The tires may be under-inflated. Flat tires create a lot more drag than you might think on a car, mostly by increasing the rolling resistance. Finally, the tires might be slightly different sizes - if the new tires are a little bit bigger, then one revolution would take you a little bit further than with the old tires, and yet since the distance is calculated by tire revolutions, the car would think you had gone the same distance. If you get on the highway and set the odometer at a marker, give it 10-20 miles and see how close you are to the markers with the odometer - you may be off by a little bit, which would effect the reported milage (since you're distance is actually greater than that recorded).

While i'm not a tire expert here, many people seem to be... if you post the specifics of the tires you put on the car, someone may be able to chime in with the differences and such.

 

<div class='quotetop'>QUOTE(Jim C @ Oct 16 2006, 05:59 PM) [snapback]333731[/snapback]</div>

Jim Your Michelin's were (are) Low Rolling Resistance (LRR) tires. Your new ones seem to not be LRR. One other factor may be to look up the Revolutions per mile of the two tires (you can find the specs on tirerack.com for most tires). If the new tires have a lower revs/mile, your speedometer-odometer readings have changed calibration which can account for part of the difference (not a real change in MPG).

JeffD

 

<div class='quotetop'>QUOTE(jdenenberg @ Oct 17 2006, 11:11 AM) [snapback]333920[/snapback]</div>

I just recently checked my tire pressure (I hadn't done it since I took delivery on the car). The pressures were all ~32lbs. I raised the pressure to 40 front 38 rear. My gas mileage increased by 4 -5 MPG. By the way Jim, I presume you are talking about Imperial gallons.

 

<div class='quotetop'>QUOTE(syclone @ Oct 17 2006, 12:36 PM) [snapback]333959[/snapback]</div>

I don't know if it was my tires, but since my first tank of gas was 30 mpg, I pushed my tire pressures from 32 to 40/38...I now get 42 mpg pretty consistently, but I still only have 1100 miles on the car...so hopefully, that will go up. I checked pressure yesterday and my front OEMs had dropped to 38...I feel as though the car rides better with the pressure a little lower...I will stay at 38 for a bit, then go up again, perhaps to 42/40...and see.

terri

 

Have patience. The car is not even broken in yet. You will see an increase of the MPG @ 5000 miles and again @ 10k.