Sneaky Ecomodding
 

So, my friend had me drop him off for a trip (and I will be driving his car out to pick him up when he gets back), and on the way there, he mentioned that his low tire pressure light kept coming on. He asked me to do him a favor and check to make sure his tires were inflated properly.

Well, long story short, I've been meaning to do this for a while, but I don't want to mess with someone's car without their permission. Well, now, permission granted! :thumbup: I checked his tire pressure this evening when I got back from work... ~34-35 psi with a max sidewall pressure of 44 psi. :eek:

I'm going to have fun with this one. :D

You sound like the kid who just found the apple pie cooling on the windowsill, make sure you don't get sprung with pie on your face:D

I tried to help my sister in law improve the mileage of her '98 Accord by inflating the tires from {they were low} about 26 psi to 44 psi. She drove it to work one day and came back and asked me to lower the pressure. I dropped it to 36 psi and she's happy now.

We do what we can do.....

I had my wife running at 38 cold on her old car.
Her new one has a sidewall max of 51 and it's currently at 44.

...just remember to tell him "...cold tires often ride rough..." when he gets back into his car the first time.

Maybe 38-40 psi so its not so noticeable but gets the rolling resistance down?

Hope you get away with it. :D

Ladogaboy -

Are they young tires or old tires? I wouldn't try it with old tires.

CarloSW2

75% of max sidewall is always good on a P tire for starters. 33 is fine, IOW, and 36-psi is probably good.

Well, 34 psi is setting his TPMS off whenever the temperature drops below 50 F. The tires are new (maybe 20k miles?... I'll have to check to confirm), but the car is a 2011 with factory stock tires. I'm probably going to pump them up to about 40 psi when I get back from work tomorrow. The temperatures look like they will start to rise again, so that should give him some room to play with the tire pressure.

Unless the tires on your friends car were under inflated is suspect there will be little change in the mileage. Some improvement would be seen if driven mostly highway miles. IMO to reap the benefit of higher tire pressure a change in driving style is required, letting off the gas sooner to take advantage of the longer roll. If this change does not occur your friend will just wear out the brakes sooner.

Good point, nemo. Luckily, I think he does enough static driving that the reduced rolling resistance will help tremendously. I have to drive about 80 miles to pick him up tomorrow, so I plan on leaving a surprise on his dashboard. :p

I think the best he's ever averaged is ~ 32 mpg... so I have a goal. I'm not a fan of his transmission, though. :(

Never heard of that before. My brake rotors have recently gotten a little gummed up from crud. I guess thats what what happens when you "never brake!"

My wife doesn't know, but she is running around at max sidewall in her truck.

Saturday is air pressure check day around here.

Why would you want to lessen the roll resistance of a pickup truck? Cheaper than a divorce?

If Ladogaboy's friend is not aware of the change and continues to drive using the same spacial references, he will need to brake harder to stop within the same distance with the higher tire pressure. This effect becomes more pronounced the heaver the vehicle, in my experience. Not that the higher tire pressure its self causes the brake wear.

I like nemo's point, because it illustrates just how important proper driving techniques really are. I guess the first adjustment really does need to be the nut behind the wheel.

Well, it wasn't as much of a success as I would have liked. I'm sure most of it had to do with driving conditions. On the same trip last week, it was dry with a slight tailwind = ~ 32 mpg. On my trip down today, it was raining with a headwind = 33.3 mpg.

I can definitely tell the difference in aerodynamics on his car, though. The difference between 55 mph and 65 mph is VERY significant. Greater than 10% according to the instant fuel gauge.