Wheels, Rims, and Tires

[NeilBlanchard]

Joe,

I had some Yokohama Avid tires on my car a while back and they are probably the highest rolling resistance of any of the tires I've had on the car. They also wear fairly rapidly.

 

[JoeS]

I had some Yokohama Avid tires on my car a while back and they are probably the highest rolling resistance of any of the tires I've had on the car. They also wear fairly rapidly.

Let's see, reading from the Yokohama website, here are a couple of quotes using marketing-speak buzzwords:

"Delivers ultra-low rolling resistance for increased fuel efficiency, without sacrificing treadlife, comfort or grip on dry, wet or snow-covered roads."

"Quite possibly the most complete tire ever created.
Yokohama is raising the bar on performance with the introduction of its all-new AVID ENVigor®! ENVigor is the first tire to collectively offer excellent traction and handling, superior comfort, long tread life and remarkable fuel efficiency. Available in 78 sizes, it is one of the largest launches in the company's history. ENVigor is so clearly in a league of its own that a new category virtually had to be created for it: "Grand Performance"!"

Like Mark Twain wrote, "...you pays your money and you takes your choice''. In our case here in the US, we have only two choices: the OEM Dunlop Enasave and these Yokohama AVID ENVigors.

Nevertheless, I'm still keeping an open mind. Two thoughts -

1) Even though I had noticed absolutely no battery degradation, after 24,000 I would have expected to see some. Could it be that my gradual wearing of the OEM tires actually further reduced their rolling resistance which compensated for a possible very gradual battery capacity degradation, keeping things constant - until I bought these new tires?

2) I simultaneously did the Misubishi Clipper Creek charger software update. Could it be that Mitsu had also programmed in a reduction of the usable battery capacity at the same time? The top end voltage is unchanged, but perhaps they increased the bottom voltage level at which the system shuts down, thus reducing the window? Edit: Whoops, that would not have any effect on the actual kWh that I measured when I recharged the car after the trip. Scrap this thought.

The good news is that this range reduction has a negligible effect in our daily driving, and will only matter if, say, I want to do that 70-mile round trip to the airport to pick someone up...

 

[jjlink]

So maybe some of can be in the tire test control group. I don't have the Mitsubishi Clipper Creek charger software update; and I will most likely replace my tires with the OEM stock tires. Our mileage on the car is about the same. Although I still have some tread left; so I maybe able to hold off for a while.

Anyone else on their second set of tires?

 

[Don]

Could it be that my gradual wearing of the OEM tires actually further reduced their rolling resistance which compensated for a possible very gradual battery capacity degradation, keeping things constant

Certainly. As the tread wears away, the rolling resistance does decrease. One of the 'tricks' employed by most LRR tires is less tread to begin with (9/32nds vs 11/32nds for 'normal' tires) as the extra tread does cost you resistance

2) I simultaneously did the Misubishi Clipper Creek charger software update. Could it be that Mitsu had also programmed in a reduction of the usable battery capacity at the same time? The top end voltage is unchanged, but perhaps they increased the bottom voltage level at which the system shuts down, thus reducing the window? Edit: Whoops, that would not have any effect on the actual kWh that I measured when I recharged the car after the trip. Scrap this thought.

I wrote you a nice reply to this the day you posted your trip results saying I *thought* you were probably experiencing normal pack degradation after 24,000 miles . . . . until I too realized this would not have any effect on your Kwh/miles computations

The good news is that this range reduction has a negligible effect in our daily driving, and will only matter if, say, I want to do that 70-mile round trip to the airport to pick someone up...

True - And more good news is your range may recover most of what it lost as the tires begin to wear

Don

 

[JoeS]

So maybe some of can be in the tire test control group. I don't have the Mitsubishi Clipper Creek charger software update; and I will most likely replace my tires with the OEM stock tires. Our mileage on the car is about the same. Although I still have some tread left; so I maybe able to hold off for a while. Anyone else on their second set of tires?

jjlink, want to do a test? We can swap wheels on our cars for a few weeks and you can try out these Yokohama AVID ENVigors and I'll see if going back to the stock Dunlop Enasaves lets my mileage return - and you could see what impact these tires have on your own mileage?

On another train of thought...

The recent rain we've had here in California seems to further exacerbate the poor mileage the Yokohama AVID ENVigor tires give. Did a wet run this morning and came back with the fuel gauge at 8 bars and yet RR = only 23 miles - ugly!

I'm one of those people who rarely returns a product after purchasing it, and then only if it is actually broken. I try to do my homework ahead of time but, with these tires, I couldn't find any comparative data on the Web and was sucked in by Yokohama's advertising: "Excellent Fuel Efficiency ADVANCED SILICA COMPOUND Delivers ultra-low rolling resistance for increased fuel efficiency, without sacrificing treadlife, comfort or grip on dry, wet or snow-covered roads."

Anyway, it occurred to me that the manufacturer might have some sort of performance guarantee. It turn out that they do, but it's only good for 30 days! http://www.yokohamatire.com/assets/docs/promise_30_day_trial.pdf My loss, as it's been six weeks now, even though I had been told that it takes about 1000 miles for the tires to "break in". Think I'll go talk to the dealer I bought them from tomorrow…

 

[jjlink]

Joe, How are you figuring your mileage? How should I baseline the mileage I'm getting now as well as during the test?

 

[JoeS]

Joe, How are you figuring your mileage? How should I baseline the mileage I'm getting now as well as during the test?

John, I have multiple points of reference:

1. The 8000 miles I meticulously measured my input energy, resulting in an overall average of 4.2miles/kWh (wall to wheels, not the same as using onboard measurements while driving). I can very easily exceed this by simply driving conservatively, which is why the careful run I did last week (3.9mi/kWh) was so disappointing.

2. Simply look at RR after the car has fully charged. We usually were in the 70's before the new tires.

3. Note your RR + Trip miles as you are driving after a full charge. This number should go up if you're driving conservatively.

4. At around 8 bars I would expect to see RR>=35miles, unless I had been leadfooting.

 

[Barbagris]

As a curiosity:

This is the graph of my consumption (wall to wheels), in the past months (since I installed a kWh counter)

The 12/11 I swap to winter tires, from alloy rims and Dunlop Enasave (energy label "C") to steel rims with Falken HS449 (front) and Continental TS800 (rear) (both labeled "F"). Both are euro brands.

Very little heating (the peaks of the graph).

Average consumption climb from 15 kWh/100 to about 17. Yes, I spend a lot.

 

[JoeS]

Wow, Barbagris, your chart starts off confirming that our normal wall-to-wheels performance is about the same (my overall average of 4.2mi/kWh = 14.8kWh/100km), and I see the rapid deterioration (i.e., mileage decrease) with those winter tires. I often wonder how much of an impact simply driving on snow and rain has, as this surely must increase rolling resistance - independently of what tires one happens to be using.

 

[JoeS]

Well, I went down to my friendly local tire dealer and explained the mileage problem I was attributing to the Yokohamas, and he went online to find some alternatives. According to him, there are ten Dunlop Enasave front tires in the country (Minneapolis) , and none at all of the rear tires (nationwide backorder). He asked me to check back in a month to see what the tire availability would be like then, as he was willing to try to work something out.

For now, we simply do more opportunity charging during the day and I'll be honing my hypermiling skills for those occasional longer trips. Truth be told, this reduced range has a negligible impact on our daily driving needs - and we put on over 1000miles/month on our i-MiEV.

 

[alohart]

According to him, there are ten Dunlop Enasave front tires in the country (Minneapolis) , and none at all of the rear tires (nationwide backorder).

That's sad to hear but not too surprising considering how few i-MiEV's have been sold in the U.S. and how few of them probably need new tires. Hopefully, sales of the 2014 i-MiEV will be considerable enough to improve the maintenance and repair parts availabilities.

He asked me to check back in a month to see what the tire availability would be like then, as he was willing to try to work something out.

Did you order 2 front tires? That should help a little, at least.

 

[JoeS]

Did you order 2 front tires? That should help a little, at least.

No, I'm holding off for now. This morning we had RR=71miles after a full charge, so maybe something is changing...

 

[jjlink]

FYI - TireRack.com has some of the OEM tires in stock.

I'm currently trying to baseline my mileage with the current tires. To complicate it I really don't want to charge to a full 100% SOC where charging stops. Since I am charging on the GE DuraStation at work which I saw turn back on the charge cycle after the car stopped charging. So now I unplug the car when it gets near 100% SOC with <1 % left to charge (I know this thanks to OVMS). Its down to like 3 amps at that point. This charge station does show the kWh used so I am keeping track of that, as well as the RR. Hopefully that will be good enough to get a good number.

 

[JoeS]

Hi jjlink,

Interesting about the TireRack OEM tire availability - I often wonder if "independent" tire dealers are somehow restricted in accessing a manufacturer's supply chain or if large outfits such as TireRack simply glom onto a batch of rare tires and don't share.

I also don't like to charge to 100%. What I do is simply keep track of the kWh I put into the car from the last time I fully charged, and it may be 1000 miles before I fully charge again - at which time I total up all the intermediate energy draws and have an accurate miles/kWh (or Wh/mi, or Wh/100km, or whatever) calculation. I had stopped doing this when I realized that heater and aircon use wildly distorts this consumption figure. After seeing CaniOn's numbers for the charging system's quiescent power draw I also belatedly realized that the much longer duration of charging at 120vac means that the consumption figures are invariably worse when using 120vac instead of 240vac.

 

[NeilBlanchard]

Some winter tires have very low rolling resistance - Nokian Hakka R's are among the lowest RR tires made. Michelin X-Ice's are also excellent.

Slush and ice and water all increase RR and lower traction. Slippage obviously has a large effect on efficiency.

Air temperature also matters - more for increasing aero drag, but also it affects bearings, etc.

 

[Don]

Interesting about the TireRack OEM tire availability - I often wonder if "independent" tire dealers are somehow restricted in accessing a manufacturer's supply chain or if large outfits such as TireRack simply glom onto a batch of rare tires and don't share

Tire Rack does indeed make special purchases in large quantities of selected tires and for sure, they don't 'share'

The best 14 inch 'Miata Tire' ever made was the Bridgestone RE-71 (developed specially for the Porsche 959) in 195/55R14 size and when Bridgestone discontinued production of that size in 2000, Tire Rack bought up all of the remaining stock - Several tractor trailer loads. Shortly, you could not find them anywhere else but at Tire Rack and since they had bought in such large quantity and evidently at a really good price, they lowered the price by about 20% until they sold out of them a couple years later. When their stock got really low, I bought 2 extra sets so I'd have them when needed

I doubt this is the case with the OEM Ensaves, but it's not at all surprising that they are currently available from Tire Rack and nowhere else - Happens all the time. Happily, TR usually beats everyone else's prices and they have warehouses scattered around the country, so shipping charges are kept to a minimum

Until I had the sidewall puncture on one of the iMiEV's front tires last fall, I had not bought a tire anywhere but from TR for about 20 years, but I needed the replacement for the iMiEV and my local guy was able to get me a pair in less than 3 hours

Don

 

[jjlink]

I ordered replacement tires from TR yesterday and they are arriving today. You have got to love the speed of TR. I don't need to put them right away but since they are scarce I figured I better get them now.

 

[JoeS]

Still getting miserable mileage with the Yokohamas on my iMiEV. Time for another tire dealer visit...

Wonder if Bridgestone is going to market these BMW i3 "Ologic" narrow tires more widely: http://insideevs.com/details-bmw-i3-bridgestone-ologic-tire-technology/? Bridgestone's special Potenza R92 (not a 'conventional' Potenza R92) on the Gen1 Honda Insight has superb LRR.

 

[alohart]

Wonder if Bridgestone is going to market these BMW i3 "Ologic" narrow tires more widely: http://insideevs.com/details-bmw-i3-bridgestone-ologic-tire-technology/? Bridgestone's special Potenza R92 (not a 'conventional' Potenza R92) on the Gen1 Honda Insight has superb LRR.

One of the necessary features of an Ologic tire is its large exterior diameter which results in a long footprint that compensates for its narrow footprint. Such a tall tire would result in a taller i-MiEV gear ratio (speedometer error, less acceleration, possibly poorer efficiency) and might not fit in the i-MiEV wheel wells. So I think a car needs to be designed to use such tall tires.

 

[aarond12]

Such a tall tire would result in a taller i-MiEV gear ratio (speedometer error, less acceleration, possibly poorer efficiency) and might not fit in the i-MiEV wheel wells.

Not to mention these tires are rumored to be between $280 and $400 EACH.