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Discussion Starter · #1 ·
Had to replace the rears on my coupe at 16,000 miles. Looks like that's about the mileage when I'll need to replace the rears on the cabriolet. I not thrilled with that.

Fronts on the coupe are still looking good at 19,000 miles. My guess is that I might hit the 25K mark before they need to be replaced. However, the cabriolet at 13,500 miles is already down to the tread wear indicators and are due for replacement.

Both cars have the same factory Kumhos on them. What's the deal with this I wonder?

As an FYI I replaced the rears on the coupe with Vredestein Quatracs. Not enough mileage on them to give them a thumbs up or down yet. But I'll likely go with that same tire for the fronts on the cabriolet. Might end up swapping the rears on the two cars to make each car have the same brand of tires all around. Only problem with that is that I'd have to dismount and remount them, since they have different wheels. The more I think about that the more I think I'll just wait a little while until I have to change the rears on the cabriolet too.

Len
2014 EV Coupe 19,000 miles
2014 EV Cabriolet 13,500 miles
 

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I think it's driven by two main factors:

The rears on the electric smarts wear more quickly because they experience more tire slip than the rears on traditional cars.
They are slipping more on initial takeoff because of the very high torque the EDs are capable of.
They are slipping more on braking because of the regen which is partially trading off for increased rear tire wear (and reducing front brake pad wear significantly).

The tires are also physically smaller (~6.9" wide by 22.6" diameter) and turn 894 revolutions per mile.
Contrast that with the tires on your E300 that are 8.5" wide by 25.3" diameter and turn 797 revs per mile.
The total surface area of tire on the smart rears is 3.4 square feet.
The total surface area of the E300D rears is 4.7 square feet.
For every 8/32nds the E300 would wear from the tire, the smart wears 11/32nds of tread for the same amount of tire wear (in volume/mass).

Though it's slightly annoying, it's probably not quite as bad as it seems if you subscribe to the idea of "don't use tires that are more than X years old" (where X is 6, or 7, or 10 or "pick any non-infinite number).
 

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These cars naturally wear out the rears fast and I bet the EDs wear even faster for the reasons stated above.

The factory Contis on my ICE 451 were down to 50% at the rear by like 10-13k miles. Swapped to Kumhos and they wore even faster.

Currently running Vredestein Quatrac 5 XL on all corners and haven't looked back. Mileage has been amazing out of them.

The Vredesteins should treat you well. They've lasted the longest of any tyre I've had and I would be interested in seeing how long they last on an ED.
 
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Discussion Starter · #4 ·
Okay, not thrilled with only 16K on the rears, but what about the fronts - 25K on the coupe and 13.5 on the cabriolet - same car almost - same tires - half the mileage.

Lots of posts about changing the front wheels and going with the same tire on all four corners. Most if not all of those posts are talking about the ICE version. Anything to it with the electrics?

Len
2014 EV Coupe 19,000 miles
2014 EV Cabriolet 13,500 miles
 

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MY08 cabrio MY09 Brabus MY21 Bolt
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Lots of posts about changing the front wheels and going with the same tire on all four corners. Most if not all of those posts are talking about the ICE version. Anything to it with the electrics?
Seems that there are only a couple ED owners that have gone 4 square with their tires/wheels. The major benefit is being able to rotate and improved ride/handling @ higher speeds. Yes, as has been mentioned the combination of rear wheel drive and regeneration seem to take it's toll on the rear tires.

Physics might suggest that the heavier front tire/wheel and the aerodynamic impact of a larger front tire might reduce your range BUT, with such limited range - don't think it would be that impactful?

Likely those who travel the highways would see the most impact while city travelers would see little?

One of our ICE smarts has been 4 square since 2008 and we are contemplating such a change for our ED in the not too distant future.
 

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Discussion Starter · #6 ·
Thanks - yeah, the way I drive mine, I'll probably just leave it as it came from the factory - more work for me if I would then have to rotate my tires. :)

Len
2014 EV Coupe 19,000 miles
2014 EV Cabriolet 13,500 miles
 

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I purchased a set of rear wheels for the front of my 2015 ED. I currently have 20 mm spacers behind the OEM front wheels, and have a front wheel alignment that minimizes the amount of toe-in.

With the rear wheels installed up front with no spacers, absolute grip is increased but understeer is actually a bit worse than front wheels + spacers + alignment. Transitional cornering behavior can be faster but the car settles slower. Steering sensitivity is a bit worse and at the limit grip behavior is noticeably worse. There is inadequate shock control for the amount of grip that is provided by having a set of rear wheels up front. Directional stability in crosswinds and on grooved pavement is a bit better with the rear wheels up front but overall the benefits are overshadowed by the downsides for me.

So now I have a set of rear passion wheels for sale.
 

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Discussion Starter · #8 ·
Well that's not a very good sales pitch. :)

Len
2014 EV Coupe 19,000 miles
2014 EV Cabriolet 13,500 miles
 

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Well that's not a very good sales pitch. :)

Len
2014 EV Coupe 19,000 miles
2014 EV Cabriolet 13,500 miles
I know!

I think that for many/most people, having rear wheels up front is a worthwhile upgrade. It does partially correct what is a major complaint, that being sensitivity to road grooves and sidewinds. But it also raises the front suspension height on an already tall and tippy vehicle, and IMO there's not enough spring rate/roll control/shock damping for that much grip on a tall vehicle.

That being said, I'm coming from the viewpoint of having had two very low slung vehicles with different design goals than the smart, so it's easy and almost certainly accurate to say I am pickier than most.

I do think the range would be affected by some noticeable amount. Just the ride height increase would make aero more an issue at freeway speeds, and wider tires have more frictional loses during any kind of turning. I'd guess somewhere around a 3-5% decrease, so 2-4 real world miles per charge.
 

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I just replaced my rear tires at 27K miles on my 2014 ED. I went with Continentals, $10USD more than the Kuhmos and 80K wear guarantee - ha ha. No way these tires are making it 80K miles on this car. We will see if the tire place makes good on the warrantee.
 

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I just replaced my rear tires at 27K miles on my 2014 ED. I went with Continentals, $10USD more than the Kuhmos and 80K wear guarantee - ha ha. No way these tires are making it 80K miles on this car. We will see if the tire place makes good on the warrantee.
Typically, the tire treadwear warranty is reduced by half in the case where tires can not be rotated. Still, a 40k warranty should still get you some prorating on a new set down the line.
 

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I just replaced my rear tires at 27K miles on my 2014 ED. I went with Continentals, $10USD more than the Kuhmos and 80K wear guarantee - ha ha. No way these tires are making it 80K miles on this car. We will see if the tire place makes good on the warrantee.
Typically, the tire treadwear warranty is reduced by half in the case where tires can not be rotated. Still, a 40k warranty should still get you some prorating on a new set down the line.
Good to know, thx!!
 

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Good to know, thx!!
Tread wear warranty information is in this document. See the bottom of page 6 for information on staggered setups.

http://continentaltire.custhelp.com/ci/fattach/get/34306/0/session/L2F2LzEvdGltZS8xNTY3NTIzNTgwL2dlbi8xNTY3NTIzNTgwL3NpZC9mVXJqQ0Z3WXNJS2dmR2o0cHNRQ1dQV2RBeWtkZmtnUzkyZ1RvWDhZdXVhQkJWWWJZUHBRJTdFdm1ObDVqa0lzSVIxMHhMelpTNklXb2V6Qng4eWZBUERlUllITHVUREo4c1M0NTl4UENIcDROTkdDaFdMUU5uMGpfZyUyMSUyMQ==/filename/1_2018+Total+Confidence+Plan+Warranty.pdf
 

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2009 451 Rally Red, Pennzoil Platinum Euro 5W-40, Wix XP 51356, 185/55R15 tires, 44 psl
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I found I get better mileage, and better tirewear by adding air...

Look at the sidewall of the tire, it should say “Max Pressure 44 PSI”, or “Max Pressure 51 PSI”...

I put 32 front, 35-37 rear in the 44’s,
35-37 front, 44 rear in the 51’s...
 

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I put 40 in the rears and 33 in the fronts - it does seem to improve the tire wear. And of course, less rolling friction.
 

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I have owned 4 smarts. Every one of them wore the tires out exactly the same way.
Rear tires down to 2-3/32 by 15-16K miles. Fronts last twice as long, replace at 30K. Really didn't seem to matter what brand. Right now i am running ATR-K economist and just replaced the rears after 16K miles. Fronts are still around 6/32.
 

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im wondering if it is the two different sized tires and rims? when i had my slk230 mbz, the tires would wear out at 25k or less even though they were rated 40k or 50k. the dealer said make all rims the same and tires the same. i did. the tires lasted forever almost, well beyond their 50k guranteed miles. im wondering if the same would occur if i did the rim and tire switch on my 451 smart???
 

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im wondering if it is the two different sized tires and rims? when i had my slk230 mbz, the tires would wear out at 25k or less even though they were rated 40k or 50k. the dealer said make all rims the same and tires the same. i did. the tires lasted forever almost, well beyond their 50k guranteed miles. im wondering if the same would occur if i did the rim and tire switch on my 451 smart???
Many rear wheel drive cars with either a sporting pretense or a significantly rearward weight bias specify alignment settings which are not tire friendly but do create more stability for an average driver should they do something like drive quickly and then panic and get off the gas suddenly if the rear end loses traction. For a front wheel driven car, this isn't as much of an issue for many reasons, one of which is that the average driver is much more likely to react in a proper manner if the front wheels lose traction before the back wheels do.

We corner faster in our smart than 90% of the cars out there and our tire wear in our ED is pretty even. We're approaching 19k miles on the OEM Kumhos and still have another several thousand miles of tread depth left.

It doesn't seem like changing out the front tires would affect the absolute wear rate of the rear tires, though the set as a whole could last longer if you were able to and did rotate the tires.
 
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