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Put some air in those tires!

Posted: Sat Apr 09, 2011 11:14 pm
by DarkStar
Stopped by Harbor Freight today and picked up one of these:

Image
12 Volt, 100 PSI High Volume Air Compressor

I found it interesting that while the door label states a pressure of 36 PSI the factory installed tires have a maximum pressure rating (cold) of 44 PSI. Since we could technically put whatever tires on the vehicle we wanted to, I thought about the pressure situation and decided the tires probably know best on how many PSI they can handle, so I filled them up!

The efficiency difference between 36 PSI and 44 PSI should be very, very small, however using the portable 12 volt air compressor makes it really easy for me to now check my air pressure during my lunch break once a week.

Re: Put some air in those tires!

Posted: Sat Apr 09, 2011 11:54 pm
by garygid
Has anybody tried using the Air Compressor that comes with the LEAF?

Can it be used WITHOUT the can of "goo", just to inflate
slightly-soft tires?

I would expect there to be a noticable difference in "rolling
resistance" between 36 and 42 psi.

Re: Put some air in those tires!

Posted: Sun Apr 10, 2011 12:08 am
by LakeLeaf
garygid wrote: I would expect there to be a noticable difference in "rolling
resistance" between 36 and 42 psi.
I would expect that too. There certainly is with other LRR cars.

Re: Put some air in those tires!

Posted: Sun Apr 10, 2011 3:13 am
by Randy3
garygid wrote:Has anybody tried using the Air Compressor that comes with the LEAF?

Can it be used WITHOUT the can of "goo", just to inflate
slightly-soft tires?.
Yes, I have used the air compressor that come with the LEAF. It works fine without using the "goo" that comes with it. By the way, it's the same air compressor that came with the smart car that I sold when I bought my LEAF.

I notice that http://www.tirerack.com has the OEM LEAF tires now.

Re: Put some air in those tires!

Posted: Sun Apr 10, 2011 6:16 am
by mwalsh
LakeLeaf wrote:
garygid wrote: I would expect there to be a noticable difference in "rolling
resistance" between 36 and 42 psi.
I would expect that too. There certainly is with other LRR cars.
I went to 40lbs last week and, yes, I do seem to be doing a bit better, particularly (for some reason I don't really understand) at higher speeds.

Re: Put some air in those tires!

Posted: Sun Apr 10, 2011 7:10 am
by garygid
$92 + $18 ship for one tire.
$92 each + $53 ship for 4 tires
(shipping from Nevada to 92653 in Orange County, CA)

I think we are still working on getting a price from a Nissan dealer, right?

And, no price yet on a rim, either OEM or a much lighter but same-size rim, right?

Re: Put some air in those tires!

Posted: Sun Apr 10, 2011 8:12 am
by DarkStar
Randy3 wrote:Yes, I have used the air compressor that come with the LEAF. It works fine without using the "goo" that comes with it. By the way, it's the same air compressor that came with the smart car that I sold when I bought my LEAF.
That's very interesting! I didn't even bother trying to use the Continental air compressor because all the info I ever found on it seemed to indicate that it needed the tire sealant installed on it to function properly.

Re: Put some air in those tires!

Posted: Sun Apr 10, 2011 8:18 am
by TomT
Sigh... Once more: The pressure on a tire's sidewall is the maximum allowed for that tire, not the recommended operating pressure. Rarely do you or should you run a tire at that pressure. Example: The tires on my BMW are very high performance tires and have a sidewall rating of 48 pounds. The recommended pressures for my car are 29 front/33 rear with normal load and 33 front/37 rear for maximum load. I run the latter. If I ran that car at 48 pounds not only would it ride like a truck, but the handling and braking would be significantly degraded. It would also be much harder on the suspension. But yeah, I might get a few extra tenths in mileage and a little better tire life... The tradeoff is not worth it in my opinion.
DarkStar wrote: I found it interesting that while the door label states a pressure of 36 PSI the factory installed tires have a maximum pressure rating (cold) of 44 PSI. Since we could technically put whatever tires on the vehicle we wanted to, I thought about the pressure situation and decided the tires probably know best on how many PSI they can handle, so I filled them up!

Re: Put some air in those tires!

Posted: Sun Apr 10, 2011 8:51 am
by DarkStar
mogur wrote:Sigh... Once more: The pressure on a tire's sidewall is the maximum allowed for that tire, not the recommended operating pressure. Rarely do you or should you run a tire at that pressure. Example: The tires on my BMW are very high performance tires and have a sidewall rating of 48 pounds. The recommended pressures for my car are 29 front/33 rear with normal load and 33 front/37 rear for maximum load. I run the latter. If I ran that car at 48 pounds not only would it ride like a truck, but the handling and braking would be significantly degraded. It would also be much harder on the suspension. But yeah, I might get a few extra tenths in mileage and a little better tire life... The tradeoff is not worth it in my opinion.
So if you installed tires onto you Leaf that had a maximum sidewall pressure of 34 PSI you would still run them at 36 PSI per Nissan's sticker on the car? Probably not... If the tire is sized properly for the wheel it is mounted to, the tire manufacturer would know best what their tire should be inflated to, not the vehicle manufacturer. The information I've found also has stated running maximum sidewall pressure will decrease the possibility of hydroplaning and improve handling & braking.

Just a quick update on my experience though, we drove the car around a bit last night and I didn't notice any changes in the handling or "firmness" when hitting various bumps and potholes, definitely not "harder" on the suspension (though if I lost a few pounds that would probably help a bit)... :D

Re: Put some air in those tires!

Posted: Sun Apr 10, 2011 8:57 am
by DeaneG
DarkStar wrote:...If the tire is sized properly for the wheel it is mounted to, the tire manufacturer would know best what their tire should be inflated to, not the vehicle manufacturer...
Absolutely not. The correct pressure for the tire depends on the load (weight) which the car places on it and suspension setup and characteristics. The tire manufacturer does not control this. The tire manufacturer's (sidewall) pressure rating is the maximum pressure which could be used without risking blowing the tire sidewall or blowing it off the bead. It is by no means the "best" pressure for the tire, unless you value energy efficiency above your life.