Tire pressure mpg tests - tire inflation

You can't get to the "bottom" of sand, so you need to float on top of it. You can get to the bottom of snow... and you must or you will be floating on top of it.

 

Thowing out my pressure to MPG results - running on the dealer's pressure of 35 I got about 52.5 MPG. When I raised the pressure to 42/40 I immediately started seeing 56-57 MPG. I was amazed and very pleased!

Any reason to think the Ecopia's I have on the car won't perform well in the winter on plowed, but sometimes messy roads? I'm willing to give it a shot this winter and switch out to an other tire if I feel like I'm slipping around too much.

Thanks!

 

I may have spoken too soon...those 60 miles weren't my usual commute. I reset my trip computer at the beginning of the week and it now looks like the pressure increase bumped me up 3 MPG, with no noticeable change to ride comfort.

 

Interesting thoughts.. but I am going to go with the "snow is different from sand" theory (and the ice skate analogy) and increase the pressure instead of lowering it this winter. Will report back

 

Yes... but you'd be wrong. You want as much tire and tread on the ROAD as possible and the best way to do that is to raise the tire pressure to reduce the footprint and let the tire sink past the snow and onto the road surface.

Same as for water, hydroplaning is very dangerous in south florida and under-inflated tires make a car more susceptible to hydroplaning.

 

Sphyrna, agreed!
Another analogy, the beach baby strollers with the large air filled wide tires to float on the surface as opposed to the WWII willys jeep with the very narrow but deep tires which allowed for below surface traction. Since none of us will be driving on deep beach sand, we can use that theory on the snow.

 

That's what I was saying: you cannot get to "the bottom" of sand, so need less tire pressure for maximal surface area, to float on the sand. But with snow, you need a firm tire, to cut through the snow down to the road surface.

 

Yes, I agree with you. I was responding to LakePrius's post (should have quoted that instead), which is what I originally thought as well, but after reading yours and other posts I think the less is more theory makes more sense when it comes to snow and rain.

Which is interesting because when I bought my 05 and saw how lousy the stock tires were in the rain, I lowered the pressure to try to increase traction. Now on my 2010 I will try raising it to see whether it makes these LRR Ecopia tires reasonably safe in the rain and minimal amount of lush and snow we usually get...

 

If you want to see the difference air pressure makes in the rolling resistance of tires, try this. Ride a bicycle a couple of miles with the tires half flat, then a couple of miles with the tires at max pressure. It will come home solidly, I promise you.

 

I thought we'd already done this as kids, and it doesn't take a couple of miles as I recall. I can still feel my legs aching..........

 

What are the implications of all this on the 17" wheels for the V? I'm nervous about exceeding what the manuf recommends (they did it for a reason)...but I just checked my car and upon delivery it was in excess of 41 PSI per wheel. I bled it down to 33/32. I'll update you with the diff after the weekend (roadtrip).

 

I just did that, and with your tires (see final results below)

Most pe0ple with sidewall max or above say wear improves. Not sure about that, I guess it's becasue the new, low-rolling resistance tires don't bulge as much.

 

Thanks for the chart... I know you went to allot of trouble.

You read it as 2.5mpg increase for 30psi.

I saw it more as roughly 1mpg inprovement for every 10 extra psi you run in your tires. "easy to remember"
That tells me that going into the danger zone is not worth it.

I used to run 60psi and did it for quite a while till I hit the edge of an asphalt road where it had broken and it blew out my tire!

That got my attention!..... Running without rupturing is one thing, but hitting something is quite another!

If you want to be able to hit a rock, curb or any unexpected object lying in the road without having a blow-out, I wouldn't dare above 40psi as the sudden increased momentary air pressure rise is just too much.

I currently run at 42psi now.... I don't like the grainy feel on the road at higher psi's.

I feel it wears on the shocks and suspension more too as tires are the first line of suspension and cushioning.

For me, 40psi gives the best balance of mpg, steering tightness and control along with the luxury ride a nice car gives... seems if I run too high, my car starts feeling less "luxurious" and harder... almost like the suspension is worse....

Just my preference.... for what its worth.