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Re: Put some air in those tires!

Posted: Mon Apr 08, 2013 5:40 am
by RLewisCA
Volusiano wrote:
Nubo wrote:
RLewisCA wrote:...Overinflation will often result in additional cabin noise, as well as inferior cornering, stopping, acceleration and wet performance. Both conditions will likely produce uneven and premature tire wear. Over-inflation in particular will produce premature wear on the center 1/3 of the tread. This can be especially dangerous in wet weather because the car owner may look at the outer tread, see there is sufficient depth to drive safely, however the center of the tread could be almost fully worn, and because the tire is over-inflated, the center of the tread is supporting the most weight and making the most consistent contact with the road.

If driving in wet weather, if the center of the tread does not have sufficient depth to evacuate the water on the road from the tire's surface, this will result in hydroplaning.

The point is - follow the recommended PSI from the vehicle manufacturer, found inside the driver's door jam - not the psi molded onto the sidewall of the tire. Not doing so will most certainly void your tire warranty.
Interestingly, I've read a number of reports of the LEAF OEM tires, at Nissan-recommended pressures, which experienced excessive shoulder wear.
I can back this up. My LEAF's tires barely lasted me 17K miles before I had to replace them due to excessive shoulder wear. I don't drive my LEAF aggressively at all. Had them rotated at 7.5K and 15K per mfg recommendation.

I hear what you're saying, but shoulder wear can result from a number of possible factors, underinflation/overloading being one of them. Other factors include improper alignment (toe in or out, camber positive or negative) or tires being out of balance. So, without an inspection of the tires it would be impossible to determine which was the primary factor, or if it was a combination of two or three of these things. Additionally, the tires on my SL are 'V' speed rated tires. Why, I don't know, since V rated tires are represent a bit of overkill (rated for 149 mph). So, I would not expect them to last much beyond about 20,000 miles if they wear nice and even.

Also, it would not be difficult to calculate the proper tire inflation for an OEM tire to check if the manufacturer's recommended pressures are correct. All you would need is the curb and max weight at each wheel on the Leaf (service manual maybe?), and the tire manufacturer's load chart for the tire (which shows how much weight the tire can support at a variety of pressures).

Re: Put some air in those tires!

Posted: Mon Apr 08, 2013 6:35 am
by DaveinOlyWA
I am not a tire expert. I am just a person who has run my PSI at 42 for 15 years over 5 different vehicles. During this time i never replaced tires before their rated mileage or have i ever had a tread depth vary by greater than onemillimeter

Re: Put some air in those tires!

Posted: Mon Apr 08, 2013 7:44 am
by Nubo
RLewisCA wrote:I hear what you're saying, but shoulder wear can result from a number of possible factors, underinflation/overloading being one of them. Other factors include improper alignment (toe in or out, camber positive or negative) or tires being out of balance. So, without an inspection of the tires it would be impossible to determine which was the primary factor, or if it was a combination of two or three of these things.
Out of all of those factors, which would result in high wear on both shoulders but not on center tread?

My approach is to bracket the inflation pressures, drive for awhile and decide by handling. I've done this on other cars and sometimes ended up within 2 or even 1 PSI of the recommendations. In the case of LEAF, however, I ended up at 44 PSI. I do agree that wear should be taken into account. That takes longer to assess, of course. It took me about 2000 miles to settle on 44psi, and I'm still under 12000 miles, so not a lot of miles but so far the treadwear seems pretty even. If I saw evidence of excessive center tread wear I would indeed back off the pressure and for all of the reasons you gave.

The LEAF is a heavy car, and the Ecopia sidewalls are quite supple.

Re: Put some air in those tires!

Posted: Mon Apr 08, 2013 8:05 am
by TomT
Agreed. On most cars I would usually wind up at 4 pounds above the recommendation. The Leaf is the only car I have ever owned where I wound up 8 pounds above the recommendation... Regardless, I never exceed the maximum pressure stamped on the sidewall.
Nubo wrote:My approach is to bracket the inflation pressures, drive for awhile and decide by handling. I've done this on other cars and sometimes ended up within 2 or even 1 PSI of the recommendations. In the case of LEAF, however, I ended up at 44 PSI.

Re: Put some air in those tires!

Posted: Mon Apr 08, 2013 2:05 pm
by mkjayakumar
All these discussions made me inflate from 36 to 38 PSI over the weekend on my Leaf.

44? I am worried it is going to blow up on my face right when I am inflating it. 38 will do for now..

Re: Put some air in those tires!

Posted: Mon Apr 08, 2013 2:10 pm
by DaveinOlyWA
mkjayakumar wrote:All these discussions made me inflate from 36 to 38 PSI over the weekend on my Leaf.

44? I am worried it is going to blow up on my face right when I am inflating it. 38 will do for now..
if you are *that* concerned. set the PSI to 44 lbs now and then come June, lower it to 40.

keep in mind, Summer time heat will put your PSI over 50 on warmer days. still well within the tire's capabilities

Re: Put some air in those tires!

Posted: Mon Apr 08, 2013 9:53 pm
by ILETRIC
38 is a very good number for 44 tire. You could go higher (39-40) in winter but in summer 38 is perfect because in summer as tire heats up at freeway speed the pressure increases to 41-42 or higher. (Measure hot tire and then the same tire in am and you will see the difference.)

They say not to go over maximum which would be 44 hot. That's why 38 cold is a good number.

My Ectopias lasted 30,000 miles but by the time we got to that number they were illegal. I have immediately switched to low resistant Michelins (can't think of the name right now) and the cornering got better. Very solid tire. Total bill about 800 bucks at Costco - special order. 50,000 mile tire with mileage warranty. I'm hoping to stretch them to 60,000 at least.

Re: Put some air in those tires!

Posted: Tue Apr 09, 2013 6:17 am
by DaveinOlyWA
The tire rating is "cold" pressure

Re: Put some air in those tires!

Posted: Tue Apr 09, 2013 7:03 am
by derkraut
DaveinOlyWA wrote:I am not a tire expert. I am just a person who has run my PSI at 42 for 15 years over 5 different vehicles. During this time i never replaced tires before their rated mileage or have i ever had a tread depth vary by greater than onemillimeter
Same here----I couldn't have said it any better. I'm running 44psi cold, very little noticable wear after 11,000+ miles. No problems whatsoever with noise, handling, etc, etc.

Re: Put some air in those tires!

Posted: Tue Apr 09, 2013 8:26 am
by EVDRIVER
50 PSI on the original tires and the same on the MXVs.