Tire pressure mpg tests - tire inflation

[harbormaster]

Curious if anyone with the 2010's have adjusted tire pressure and tracked the mpg numbers?
My car came with the Avid S33 tires (p195/65 r15)
Had the following pressures after two weeks of driving (only 600 miles)
front driver side - 35
front passenger side - 34
rear driver side - 34.5
rear passenter side - 34.5

I will bump them up to 36 front and 34 rear.
Of course the car door has specs has 35 front and 33 rear.
The tire max pressure is 44.

I don't want to over inflate too much and cause wear.

Our minimal miles so far (not using the computer) have been
46.8 (computer est. was higher)
48.9 (computer est. was higher)
current computer reads 52.4 - I hope when I double check on the next fill up it support the computers optimistic est.

Thoughts ?

[a64pilot]

I'd go to 44. I doubt that 1 psi would make a measurable difference. I assume if you do nothing at all, your mileage will improve as the car breaks in and you learn the car wouldn't it?

[jay_man2]

I have the Bridgestone Ecopia's and they were at 40 all around at delivery. I bumped the fronts to 42 after a week of ownership. My mileage on the MFD has been 54.8, 58, 55.1, 51.4 (stopped driving like granpa) and now 54.2 through half a tank.

The computer readout will always be 1-3 miles higher, with a wider spread the higher it reads.

[tumbleweed]

Inflating the tires to 42 or 44 psi will most likely not cause excess wear. Somewhere in the Gen2 threads is a picture Hobbit took of the tires that came off his '04 after a lot (don't remember how many) miles. He kept them at over 40 psi for all of those miles and they were still worn more on the outside edges that the middle. I didn't keep the original tires on my '05 that long but they were starting to show the same wear tendencies and I used 42 psi in all 4 corners.

Higher tire pressures usually result in the following:

A slightly firmer ride,
Slightly decreased traction on dry pavement,
Increased resistance to hydroplaning,
Less rolling resistance and thus better fuel economy.

Modern radial ply tires don't seem to get bowed out and wear in the middle when they have more air in them like bias ply tires did. The belts seem to keep the tread nearly flat.

I will increase mine when my Gen3 arrives and post the results at several different pressures.

[charlieh]

I have run my 04 at 42/40 since I got the car, and the mpg is definitely better than running at 36/34. I have good tread left at 38,000 miles. I am running the Ecopias on my 2010 at 42/40 and I am not done with my first tank, but I am currently at 60.4 mpg (mostly city and some freeway). I think I will try 44/42 and see how that works.

[harbormaster]

Originally Posted by charlieh

I have run my 04 at 42/40 since I got the car, and the mpg is definitely better than running at 36/34. I have good tread left at 38,000 miles. I am running the Ecopias on my 2010 at 42/40 and I am not done with my first tank, but I am currently at 60.4 mpg (mostly city and some freeway). I think I will try 44/42 and see how that works.

Thank you all for the great feedback. Just curious how noticable the ride changes with the higher pressure. I can't seem to find any car or tire warranty issues at first read of the manual.
Anyone have any preference as to regular air vs nitrogen?

[tumbleweed]

Originally Posted by harbormaster

Thank you all for the great feedback. Just curious how noticable the ride changes with the higher pressure. I can't seem to find any car or tire warranty issues at first read of the manual.
Anyone have any preference as to regular air vs nitrogen?

I don't think it makes much difference in ride, actually I prefer the car to ride a bit firmer anyway. You just need to try it.

There has been a lot of discussion on this site about nitrogen in tires. The consensus is that there is no advantage to using it in passenger car tires. After all the stuff we breath is already 78% nitrogen and that's good enough. Personally, if I buy tires at Costco and they want to put in nitrogen that's fine but I wouldn't pay someone extra to do it.

[harbormaster]

Originally Posted by tumbleweed

I don't think it makes much difference in ride, actually I prefer the car to ride a bit firmer anyway. You just need to try it.

There has been a lot of discussion on this site about nitrogen in tires. The consensus is that there is no advantage to using it in passenger car tires. After all the stuff we breath is already 78% nitrogen and that's good enough. Personally, if I buy tires at Costco and they want to put in nitrogen that's fine but I wouldn't pay someone extra to do it.

I have been the same way on the nitrogen. Tires are often from Costco, just yesterday as a matter of fact on my sons 96 honda civic (still a young one only 230,000 miles - on its fourth deer though - looking like Marty Feldman)
I have just increased the pressure on the Prius to 42/40.
I will post results.
thx

[Spartane]

Originally Posted by harbormaster

Thank you all for the great feedback. Just curious how noticable the ride changes with the higher pressure. I can't seem to find any car or tire warranty issues at first read of the manual.

Just last night I bumped the air pressure up to 42/40 for the Ecopia EP20 tires on my 2010. I was worried about a rough ride, but that didn't seem to happen.

I reset trip-B before my trip to work this morning, and the car registered 3.1L/100km (75 mpg US) versus the more typical 3.4L/100km (69 mpg US) that I had been getting. So it looks like my fuel economy might have jumped by as much as 10%. (Note that I'm not actually getting 75 mpg; I've found that my car's display is overly optimistic -- also by about 10%).

An unexpected bonus; handling on the highway got better in that fewer micro-corrections in steering were needed to keep the car running in a straight line.

[MSantos]

The Ecopias on the 2010 will be running at 55+ psi in the front and 52 in the rear merely as a start.

At these pressure levels, the wear is significantly lower and the tires run much cooler (as indicated in the TPMS). That's the way I always pressed the tires on all my hybrids and other than the slight loss of comfort over rougher surfaces, the MPG and the safety are decidedly higher.

Cheers;

MSantos