Winter tires

We have had the 2012 Nissan Leaf for 4 year plus 6 weeks now. This winter was snow and ice on the roads in Kansas more than last year but not as much as the first winter we owned the leaf, and the tires were not gripping the road. Even when the Leaf was new the Bridgstone fancy tires that came with the car did not grip well but this year due to 35,000 miles on the car it was especially bad since the tires where near the end of their useful life. So I got new tires and went with a cheap all-season uniroyal 102$ each tire. My wife, the main driver of the Leaf was much happier with it really holding the road and did a great job on the snow and ice. So my question is does it make sense that the Leaf with the new tires is getting 3.9 miles/kWh as opposed to last winter 4.2 miles/kWh, is it the tires? I am thinking of just leaving these tires on the car all summer, they are all season. Is there a reason not to? My wife drives the car 20 miles/day, yes it will consume more energy but even on the worst day where she runs around and does some shopping or has a dentists or other doctors appointment including driving to work, picking the kids up from school, she never goes over 50 miles in a day.

Yes new tires always have a higher RR(rolling resistance) than worn tires, happens all the time. Note your new tires should get better after they've worn in a bit but if they aren't LRR(low rolling resistance) tires, they may never get as good as your OEM tires which were geared for maximum mileage.
A/S tires are fine to drive in the summer, snow tires on the other hand are NOT recommended when the temps get much above 40F, they will wear out much quicker in warmer temps.

in a perfect world I'd have two sets. 1 for when there is a chance of snow and 1 for when there is pretty much no chance.

I'd run the winter set from November through to mid-march (here in Utah) and the summer set from mid-march to the start of November.

if I only had 1 set of tires.. i'd run them the whole time on the all-season but I'd be hating the loss of range if it mattered to me.

Not to be flippant, but I think you asked several rhetorical questions

So my question is does it make sense that the Leaf with the new tires is getting 3.9 miles/kWh as opposed to last winter 4.2 miles/kWh, is it the tires?

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Hard to be sure, maybe? Too many variables...

I am thinking of just leaving these tires on the car all summer, they are all season. Is there a reason not to?

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It sounds like you're not too worried about rolling resistance and the related impact on range, based on this comment:

My wife drives the car 20 miles/day, yes it will consume more energy but even on the worst day where she runs around and does some shopping or has a dentists or other doctors appointment including driving to work, picking the kids up from school, she never goes over 50 miles in a day.

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So, as long as you're otherwise happy with the way the tires perform, then there's nothing wrong with using cheaper tires. Obviously, if you needed the range, then LRR tires would be the way to go.

Some folks claim that over-inflating your tires (check the sidewall PSI rating if you decide to try this) will improve range, but empirical testing seems to suggest otherwise:

https://goo.gl/Af1zMW

I personally don't over-inflate my Leaf's tires, but I'm sure others will chime in with contrary opinions. To each his/her own

A/S tires are ok for summer use but don't expect maximum road performance.

I have all season tires, but you're doing a lot better than I. I averaged about 2.5 miles per kWh this winter. Then again part of the winter I just left the tire chains on and also had to use the heater a lot, especially when it got down to -36°F. Driving through the thick slush as the compacted snow melts has also made it hard to get good mileage.

Tire rolling efficiency from best to worst, usual order:
LRR summer tires, summer tires, AS tires, All-Weather tires, studless winter tires, studded winter tires


Tire grip in summer from best to worst:
Summer tires, LRR summer tires, AW tires, AS tires, studless winter tires**, studded winter tires*

Tire grip+efficiency on very wet road:
All except LRR summer tires & studded winter tires can have excellent results. AW & AS tires should be leaders here

Tire grip in cold weather (below freezing) on clean road from best to worst:
studless winter tires, AW tires, studded winter tires, AS tires**, summer tires*, LRR summer tires*

Tire grip on ice or compacted frozen snow from best to worst:
studded winter tires, studless winter tires, AW tires, AS tires*, summer tires*, LRR summer tires*

All-Season tires are in bold to explain how inferior in the "best to worst" list they are in many scenarios.


*not acceptable
**almost not acceptable

Over-inflation does help with fuel economy. I've verified that. But up to a certain point, which is not extremely
far away from nominal value. I would recommend to stay +10% from nominal value for optimal ride comfort
and better rolling resistance.
Gain comes from less tire sidewall squish during driving. There is a point where reducing deformation is hardly measurable.
Less tire deformation means more bumpy ride. While also means no energy wasted on dampening.
Stiffer shock absorbers would also add to range slightly.

LRR tires gain better economy as the rubber itself is bending less, not the sidewall squish.
Using AS tires in summer results in exactly the opposite result of LRR tires - rubber itself is extremely soft and squishy.

If it helps,
I've put on the Michelin X ICE. They are LRR Snow tires stud less. I run them @ 41 PSI

They do great in all the conditions I have encountered so far this winter in Vermont US. They are Not as good as a studded tire and the higher pressure does reduce the grip some I think but not dangerously. The car is stable at speed on a snow covered interstate road. Crosses the slush with authority. It's more stable than the Honda Fit it replaced and I ran studs on that. I assume that can be attributed to the weight difference.
The down side is they are quite expensive. Way cheaper than body work though so I figured it is good insurance.

gregn said:

If it helps,
I've put on the Michelin X ICE. They are LRR Snow tires stud less. I run them @ 41 PSI

They do great in all the conditions I have encountered so far this winter in Vermont US. They are Not as good as a studded tire and the higher pressure does reduce the grip some I think but not dangerously. The car is stable at speed on a snow covered interstate road. Crosses the slush with authority. It's more stable than the Honda Fit it replaced and I ran studs on that. I assume that can be attributed to the weight difference.
The down side is they are quite expensive. Way cheaper than body work though so I figured it is good insurance.

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If I were to purchase winter tires X-ICE are the ones I'd chose, I like that they are also LRR and give a treadwear rating, almost all other winter tires don't even bother with a treadwear warranty. Of course it's not as high as more summer tires and you don't want to run them in the summer but I believe the TW is something like 350 as opposed to something like 600 for many summer tires.

Nokian makes very good tires: their Hakka R2 winter tires are very low rolling resistance, and they are quite good on snow and ice. Nokian is a Finnish company, and so they make good winter tires.

They also make an all weather model called the WR-G3, which I have on our e-Golf. These are low rolling resistance, but not very low, and they are not quite as good in the winter - they are great in the summer, so you do not have to change them seasonally.

For the ultimate winter tire, you can get their Hakka 8, with or without studs. These are going to be higher RR (though not bad). I have experience with the earlier gen Hakka 5, without studs.