GdB
Posts: 154
Joined: Tue Aug 12, 2014 4:06 pm

Re: Lost regen with new tires

Thu Aug 28, 2014 6:37 pm

Thanks! I guessed that after reading all your posts again and assuming you tried to find OEM sizes but the correct rears where not in stock.

So this confirms that a 0.9% difference in rear/front diameter is out of range.

BTW if you combined the 175/55 rears with half worn 145/65 fronts it would only be 2% difference, so regen might work. With completely worn fronts, I am certain regen would work.
My EVs: 2012 Mitsubishi i-MiEV and 2019 Hyundai Kona Electric SEL

PV1
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Re: Lost regen with new tires

Fri Aug 29, 2014 5:22 am

I was thinking the same thing, because I put a large gap in air pressure (44 in back, 36 up front) and that enabled regen while making sharper turns at speed, but it dropped out as soon as I straighened up. So I was really close to the threshold.

What it boiled down to was that I wasn't willing to buy Yokohamas after Joe's experience, and Dunlops are too expensive and wear out too quickly, so I went with Continental, even though the rear was the wrong size.

What is the difference with 145/65R15 up front with 175/65R15 on back? There's quite a selection at that size for the rear?
"Bear" - 2012 Diamond White Pearl ES with QC - 2/21/2013
"Koorz" - 2012 Cool Silver Metallic ES with QC - 1/5/2015
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siai47
Posts: 363
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Re: Lost regen with new tires

Fri Aug 29, 2014 8:03 am

I am surprised that you are not getting any warning lights about the ABS or other systems. The I-MiEV like most other cars has a four wheel ABS system. Each wheel has a wheel speed sensor that is calibrated so that each axle on the vehicle is reporting the same speed of the tire regardless of the actual revolutions of the wheel. In other words, software in the system compensates for the rolling radius of each tire. There is some latitude in the software that allows for corrections when you put new tires on one set of axles and not the other. However, if the change is out of the range the system can compensate for, the system usually sends a warning by shutting down the ABS or some other systems like traction or stability control. For example, many vehicles will disable ABS if it sees a compact spare on one axle. I would think in this case, the ABS is sensing a tire speed difference and turning off the regen. You can get the same effect when you hit a small bump in the road during regen that momentarily changes rear wheel speed shutting of the regen.

PV1
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Re: Lost regen with new tires

Fri Aug 29, 2014 8:16 am

Yeah, I've noticed that cutout, too.

I think I was in that range of no regen, but not bad enough for a warning, kind of like, "It's not a problem, but I'm not happy."
"Bear" - 2012 Diamond White Pearl ES with QC - 2/21/2013
"Koorz" - 2012 Cool Silver Metallic ES with QC - 1/5/2015
"Photon" - 2017 Bolt EV LT in Orange with QC - 7/31/2017

Solar-powered since 10/10/2013

GdB
Posts: 154
Joined: Tue Aug 12, 2014 4:06 pm

Re: Lost regen with new tires

Fri Aug 29, 2014 10:09 am

PV1 wrote:I was thinking the same thing, because I put a large gap in air pressure (44 in back, 36 up front) and that enabled regen while making sharper turns at speed, but it dropped out as soon as I straighened up. So I was really close to the threshold.

What it boiled down to was that I wasn't willing to buy Yokohamas after Joe's experience, and Dunlops are too expensive and wear out too quickly, so I went with Continental, even though the rear was the wrong size.

What is the difference with 145/65R15 up front with 175/65R15 on back? There's quite a selection at that size for the rear?


On radial tires, air pressure has a very small effect.

There are so many combinations that I prefer to share my excel file with the calculations. It also has a lot of other useful stuff including range calculations.
http://files.fm/g/woponqe#aa/9624Mpg_mph_imiev.xlsx
My EVs: 2012 Mitsubishi i-MiEV and 2019 Hyundai Kona Electric SEL

jray3
Posts: 1679
Joined: Tue Dec 06, 2011 1:05 am
Location: Tacoma area, WA
Contact: Website

Re: Lost regen with new tires

Fri Aug 29, 2014 11:36 am

GdB wrote:There are so many combinations that I prefer to share my excel file with the calculations. It also has a lot of other useful stuff including range calculations.
http://files.fm/g/woponqe#aa/9624Mpg_mph_imiev.xlsx


Wow GdB, that's not a spreadsheet- it's a quick reference bible for all i-MiEV performance questions!
THANKS :ugeek:
2012 i-SE "MR BEAN" 110,300 miles
2016 KIA SOUL EV, 90 kW, 27 kWh, 34k miles
2000 Mazda Miata EV, 78 kW, 17 kWh
1983 Grumman Kurbwatt EV,170 kW, 32 kWh
1983 Mazda RX-7 EV 43 kW 10 kWh
1971 "Karmann Eclectric" EV 240 kW 19 kWh

PV1
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Re: Lost regen with new tires

Thu Sep 25, 2014 10:07 am

After playing phone tag with the dealer for this whole time, my rear tires (original Dunlops) are wore to the point of being nearly smooth. With the newer Continentals on the front, I'm starting to see a drop out of regen when turning sharply. The Dunlops are wearing much faster than the Continentals.

How does this compare, time wise, to getting a replacement battery? :roll: :twisted:
"Bear" - 2012 Diamond White Pearl ES with QC - 2/21/2013
"Koorz" - 2012 Cool Silver Metallic ES with QC - 1/5/2015
"Photon" - 2017 Bolt EV LT in Orange with QC - 7/31/2017

Solar-powered since 10/10/2013

RobertC
Posts: 292
Joined: Fri Jul 27, 2012 7:35 am
Location: Winter Garden, FL

Re: Lost regen with new tires

Fri Sep 26, 2014 4:18 pm

PV1 wrote:…my rear tires (original Dunlops) are wore to the point of being nearly smooth. With the newer Continentals on the front, I'm starting to see a drop out of regen when turning sharply. The Dunlops are wearing much faster than the Continentals.
I believe that you have had your new front Continental tires for two months.
How many miles have you put on them?
How many miles do your original rear Dunlops have on them?
My original Dunlop Enasave tires still had 2/32 tread left on them at 33,000 miles.
”Red” - 2018 Red Dual Motor All-Wheel Drive Tesla Model 3 - 11/27/18
“Blue” - 2018 Kinetic Blue Chevy Bolt Premier with QC - 5/13/18
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PV1
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Re: Lost regen with new tires

Fri Sep 26, 2014 5:35 pm

I changed the fronts around 13,500 miles. I'm currently at 15,698 miles. The Dunlops have lost 2/32s in that time. The Continentals still look like new. I haven't measured them, though.

So, the Continentals have 2,000 miles on them.

The front Dunlops were changed at 13,500, and are nearly smooth on the inside 1/3 of the tire. The outsides still had a decent amount of tread left (my right wheel was pointed way out).
"Bear" - 2012 Diamond White Pearl ES with QC - 2/21/2013
"Koorz" - 2012 Cool Silver Metallic ES with QC - 1/5/2015
"Photon" - 2017 Bolt EV LT in Orange with QC - 7/31/2017

Solar-powered since 10/10/2013

kiev
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Location: The Heart o' Dixie
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Re: Lost regen with new tires

Thu Jun 28, 2018 6:01 pm

i just replaced my original rear tires at 40,996 miles--they were worn very smooth and flat, the main grooves were still showing so probably could have run them down to the bottom of the wear bars to make slicks, but there were age cracks and checking toward the inner and outer edges. i put yokohama 175/60 on this time.

i had replaced the fronts with Yokohamas, so i had nearly new front and absolutely worn out rears--and i had full regen and no issues with regen cutout.

i may try a 155/60-15 on my next front swap--it is nearly the same diameter as stock.

i still have OEM rears on kiev2 with 36k miles, plenty of tread but age cracks and checking on the edges. i will replace these with the Achilles from Amazon.

i love regen and wouldn't want to give it up, but would like to go bigger front and rear.
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