Electric vehicle thread depth

Buddy Bubs

I had one of the EVs in for its 2 year service yesterday and I was shocked to discover after 8k kms the tyres that were replaced in December (by the dealer under a service pack) are already down to 4mm, but the next part is what shocked me more

The service manager told me that the tyres on EVs are 6mm thread compared to 8mm for ICE cars, no wonder they are wearing out so fast, I know the weight doesn't help either. So, owing to the fact that tyres legally cant go below 1.6mm and all other things being equal, an EV tyre only has 4mm of thread to go through rather than 6mm before it is illegal.

I have 2 EVs which I have posted about here, I won't say which dealership I was in or which car it was, but has anyone heard of this before? I am not sure if it applies to both cars or just 1 of the brands

sh81722

https://www.boards.ie/discussion/2058346069/electric-vehicle-thread-depth

He's correct. Some of the EV tyres cheat the rating system with a lower than usual thread depth as this increases the running efficiency. Usually this results in lower than A wet weather rating as that is much dictated by the thread depth.

I got burned with Primacy-e vs Primacy when I last bought tyres. However those seem to still be be wearing well, i.e. plenty of thread left after approx. 20k driven.

prawnsambo

I know EV tyres are specifically designed for low road resistance to help with economy, tread depth might have something to do with that.. Looked up mine (Continental Sport Contact 6) and they're 7.14mm tread depth. So not exactly 8mm, but not 6mm either.

GSBellew

This is not restricted to EV's, on the W213 E Class UK spec E220d's that came with Continental Eco Contact 6 tyres had approx 6mm thread new, same size in Pirelli was closer to 8mm

User1998

Loads of tyres come with 6mm/7mm. Nothing to do with EV’s.

kirving

It's just that EV's tend to be heavier and more powerful, so the tyres are often wider, to give you a similar pressure over the contact patch. There's 1000 different tradeoffs in tyre design, and the stiffness of the tread block needs to work in unison with the stiffness of the sidewall, internal pressure, etc, so they've likely gone with 6mm for some good reason - likely fuel efficiency.

Car manufacturers often try to prioritise fuel efficiency (CO2 Emissions) over long term running costs, but this is especially true with EV's. 5% saving on a petrol car will bring you from 47 to 49.5MPG (6 - 5.7 [l/100km]), but in an EV it could bring you from 395 to 415km, which Has a much greater psychological impact in buyers.

Or I could be trying to explain away what is simply a marketing decision - people already accept that EV's tend to be harder on tyres, so why fight it when you can sell more tyres and blame the Greens?

magicbastarder

How much difference does 2mm of tread depth make to efficiency?

...Ghost...

I don't and have never purchased EV specific tyres. Load of nonsense for the sake of a couple of percent efficiency. I have always had 4 considerations when buying tyres.

1. Noise rating. EV, or Petrol, I hate hearing road noise. Noticed this on hard rubber ditch finders on a Zafira I bought second hand. They were new, but they were the first thing I got rid of.
2. Efficiency. B, or C is grand. A rating is a bonus. Again, petrol, Diesel or Whatever, you don't want your boots to be too sticky.
3. Brand. I stick to the ones I know in the premium, or mid-range. I stay away from economy crap. If I have to spend 150 a corner rather than 55, then so be it. Tyres are what keep you on the road, or from ploughing into the car in front, causing life long injuries. Trust me…I know.
4. Choose what I already have on the car if only changing 1, or 2 tyre. I like to keep them all the same. I might change brand/type if changing all 4. At the very least, I will choose a better pair than what is already there if for example I buy a used car which has decent rubber on the front, or back and I am changing one end.

Just buy the best you can afford. Change them before you "need" to.

Buddy Bubs

https://www.boards.ie/discussion/comment/122002353#Comment_122002353

They came with car, and replaced like for like on service plan. They haven't proven to be long life so I won't buy them when the time comes

kirving

https://www.boards.ie/discussion/comment/122002198#Comment_122002198

https://www.tirereview.com/the-relationship-between-a-tires-tread-depth-and-rolling-resistance/

More rubber in a tire means more heat generation, higher friction and less heat dissipation, which is why increasing tread depth increases rolling resistance, and in turn, lowers fuel efficiency.

Probably tiny in real terms, the key factor in fuel consumption in the driver. They're just all rules of thumb, and can probably be reversed by making compromises in wet performance, dry performance, cost, noise, manufacturability, wear, etc.

But when a manufacturer is trying desperately to squeeze into a lower CO2 band, or 10 more kilometers of range so that they can put 400km on the advert instead of 390km, selecting a slightly different tyre is a very easy win.

joe1303l

Similar story, Skoda EV supplied with factory 20” Bridgestone Turanza Eco Enliten with 6mm thread depth. I was sceptical that they wouldn’t last too long. To be fair the rear tyres made it to 49,000 Km’s. Recently replaced with like for like 6mm tyres covered by a service pack. No choice available according to the service manager dictated by Skoda. Front tyres still have a good bit left on them at 52,000 Km’s. On that basis, it would appear these tyres must have a pretty hard compound. I wouldn’t hesitate to buy them next time unless they’re crazy money.

KCross

https://www.boards.ie/discussion/comment/122002358#Comment_122002358

What were they?

I don’t thinks it’s a rule that all EV tyres have only 6mm. Just some manufacturers are penny pinching

My anecdote… my ID.3 came with Bridgestone Turanza ECO… melted off it after 12k km’s. Put on Goodyears and getting twice the mileage. The Bridgestones had 6.x mm when new and obviously soft. The Goodyears have 7.2mm new.

Also recently bought Hankook eco tyres.. 7mm on them too and got 30k km’s from first pair. So thread depth matters but compound too.

magicbastarder

https://www.boards.ie/discussion/comment/122002481#Comment_122002481

cheers; would be interesting to calculate to what extent (if any) the increased replacement rate of thinner tread tyres is offset by reduced fuel consumption.

for example; the article you linked claimed the difference between new and worn tyres is 20%; say (plucking a figure out of the air) buying 6mm depth tyres increases efficiency by 5%, but you got 30k out of them instead of 45k (on the rear).

if you're doing 15k a year (~€1.5k in petrol costs; i'm just making the maths easy) that 5% is worth €75. the savings on petrol, based on those figures, aren't exactly paying handsomely for the increased rate of tyre replacement. point being - the savings would be even less on an electric car.

Gumbo

My Michelin PS4 lasted 4 years and 40,034km on the rear of my M3P.

Buddy Bubs

https://www.boards.ie/discussion/comment/122002596#Comment_122002596

Same as youz Bridgestone Turanza it's the cupra born that is milling through them. I've 32k Kms on it and I'm half way through 2nd set of tyres. I'm not flooring it anymore like I was at the start. Rears are worse than the front understandably.

My etron has the same tyres in a much bigger size but there's only 12k on that car.

I won't be buying those tyres when the time comes.

creedp

https://www.boards.ie/discussion/comment/122002532#Comment_122002532

That's great longevity on what is a big heavy and torqey beast. I must give up on the GY efficient grip I've put on the not so powerful Leaf 😀 since I got it 6 years ago. The front tyres only do about 15k to 20k km and lose serious traction below 3mm. Must have a look at my receipts and see how long the rears last but I'd be surprised if they lasted 40k km.

I have Pirelli pzero on the M3 and will keep an eye on their durability. Luckily I don't really care about road noise as the stereo is always pretty loud but I do find them much noiser than any other tyre I used previously.

magicbastarder

The tyres lose traction below 3mm? Only in the wet I assume?

creedp

https://www.boards.ie/discussion/comment/122003337#Comment_122003337

Yes the traction control lights up on the least provocation on wet roads especially with lower temperatures. Back in January my tyres were below 3mm and I found them dangerous, put on new tyres and it was like night and day

kirving

https://www.boards.ie/discussion/comment/122002653#Comment_122002653

It's a good question. If I set my tyre pressure to what is recommended for "economy", they just prematurely wear in the centre and need to be replaced more quickly.

Aside from wind which made a big difference, I had a very repeatable commute each week - so kept a good eye on tyres, pressures and fuel consumption. I've tried to go with Goodyear EfficientGrip Performance as they served me well, so I don't have another brand to compare to, but I will say that accelerating hard a a toll booth just once has a noticeable effect on economy for miles, and doing it at just 2 tolls, and motorway on/off ramps effects the whole journey.

magicbastarder

https://www.boards.ie/discussion/comment/122003380#Comment_122003380

i remember fifth gear years ago doing a piece on this - worn but still legal tyres on a car, made a very big difference in very wet conditions.

https://www.youtube.com/watch?v=SdPMRMUbMuE

several comments point out (fairly!) that it's not exactly scientific.

...Ghost...

https://www.boards.ie/discussion/comment/122010516#Comment_122010516

Exactly why I change mine early. Have seen and experienced "legal" depth tyres fail and result in serious damage.