Increased efficiency with 255/45 20 Hankook Ion on my GT (updated OP)

[Mach1E]

I think I have enough experience with the tires now to provide a review.

High level: they are awesome, but they are NOT performance oriented tires.

Specifics:
1) Very quiet.
2) No "hollow" sound on road imperfections noticed at any speed.
3) At 34 psi, so smooth, and super comfortable. Low psi impacts efficiency, but holy cow these tires feel so good at 34 psi cold.
4) I can spin the tires when cold on dry pavement. I could not do this with the OEM tires. So, they are not nearly as sticky as the OEM tires. If you want to hit the curves at high speed, you will slide more than with the OEMs. I actually think sliding is fun, but it won't improve your speed in the curves for sure.
5) Because they are more slick, they should be more efficient. That is how it works. But I have not been able to gather enough data to determine if this is true or not. As I drive more, I will be capturing data via CarScanner and I will compare and determine if there is an efficiency improvement. I think there is, but I do not trust the car efficiency reading at all. I will post my efficiency measurements later when I have enough data to do that.

So in summary, I really like these tires. I am glad I went up a size even though it messes up the accuracy of the speedometer, because it means 34 psi is much more safe. And man, after running at 41 psi and then 34 psi? Amazing improvement in comfort.

Let me know if you have any questions.

You couldn’t spin the OEM tires?

Even when my GTPE tires were brand new I could spin from a stop then they spin again near 25 mph. Same goes for the 2023 GTPE loaner I got with 300 miles on it.

Now with 10k miles on them, I can spin at any speed up to and including 30 mph if I floor it. Only took about 3-4k miles before traction got noticeably worse.

I’m planning on going to pilot sport 4S 255/45 to replace them with hopes I’ll hook up.

As far as summer tires vs all seasons for efficiency, actually it’s the OPPOSITE of what you would think.

Summer have less rolling resistance and are more efficient in general-
https://tirecraft.com/summer-tires-vs-all-seasons-3-reasons-to-invest-in-performance-tires/#:~:text=Unless%20you're%20looking%20at,in%20terms%20of%20fuel%20economy.

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[mkhuffman]

You couldn’t spin the OEM tires?

Even when my GTPE tires were brand new I could spin from a stop then they spin again near 25 mph. Same goes for the 2023 GTPE loaner I got with 300 miles on it.

Now with 10k miles on them, I can spin at any speed up to and including 30 mph if I floor it. Only took about 3-4k miles before traction got noticeably worse.

I’m planning on going to pilot sport 4S 255/45 to replace them with hopes I’ll hook up.

As far as summer tires vs all seasons for efficiency, actually it’s the OPPOSITE of what you would think.

Summer have less rolling resistance and are more efficient in general-
https://tirecraft.com/summer-tires-vs-all-seasons-3-reasons-to-invest-in-performance-tires/#:~:text=Unless%20you're%20looking%20at,in%20terms%20of%20fuel%20economy.

I don't have a GTPE.

I could spin the AS tires some on wet roads, but not like these. They break free more easily for sure.

 

[azerik]

I don't have a GTPE.

And you’re not at sea level right ? ??? (this is a joke, insert bench racing laughter)

I’ll try to update the spring thread. I’ve actually turned the rebound almost off on the Koni’s with the Eibach springs. (There’s a bunch of give and take I’d want to write down to explain it.)

 

[markboris]

And you’re not at sea level right ? ??? (this is a joke, insert bench racing laughter)

I’ll try to update the spring thread. I’ve actually turned the rebound almost off on the Koni’s with the Eibach springs. (There’s a bunch of give and take I’d want to write down to explain it.)

Even with the rebound turned to minimum on the Koni's, they still have more than twice the rebound of the OEM shocks. It takes a ton of rebound to tame those OEM springs and since the Eibach springs are not as firm, less rebound would work better. Looking forward to your thoughts on this.

 

[mkhuffman]

Updated impressions of the tires:

They are so smooth, and so quiet. If you are not an aggressive driver, I think you will love them, especially if you set the pressure of the tires to 34 psi cold. It just amazes me how much more comfortable these are over the OEMs.

That's the good. Now the bad. They are slick. I was hoping that was temporary, and they would get stickier as they warmed up, but it does not appear to be the case. If, as we head into summer, I find that is incorrect, and they do grip better in the summer, I will come back here and post an update.

What are the consequences of them being slick? I have not checked stopping distance because I didn't do any testing before putting these on, but I expect they will be slightly worse. I can slide the car more easily when hitting turns very fast. And I like to hit turns fast and push the car to the limit. The limit comes earlier with these tires. I can also spin the tires easier. In the rain, it is much easier than before. On dry pavement, I notice a difference also.

I want to emphasize that these tires are NOT dangerous. They just are not performance tires. They seem to do very well in straight line water, like in heavy rain. I did a lot of rain driving at 75-80 mph, and the tires handled the wet, puddling roads very well. Just as well as the OEMs, I think. So they are safe tires. Just don't think your track time is going to improve with these.

On a side note, sliding the car is kind of fun. I liked the limit the OEM tires provided. They did slide, but they also gripped pretty well. It was a good compromise between comfort and performance, I think.

As far as efficiency goes, I have not figured out how much the efficiency has improved with these tires. I believe they must be more efficient. And I am really hoping they are, because if they are not, I am going to be very disappointed. Very disappointed. If the efficiency improves, I can internally justify the loss of performance. If not, then I will really regret getting these tires.

I have to go through all my CarScanner data to really determine if there is an improvement. And I need more warm weather driving, because temperature has a huge impact on efficiency. I think in a couple more months I should have enough data to do a true comparison.

I need to use CarScanner data because I do not trust the efficiency reading on the Sync display. The other day I got higher efficiency with the tire pressure at 34 vs 41, which makes no sense. In fact, I know that was wrong because I ended the trip with a lower SoC at 34 psi than when I did it at 41 psi, yet the 34 psi trip had a higher trip efficiency per the car. That is just wrong. So I need to go through the data to really see.

 

[mkhuffman]

Looks cool, Mike. How do they handle? I went with wider wheels and tires. The tire shop set them at 41psi (give or take a few tenths). The steering was super light and the ride was rough so I knew they were over-inflated. I dropped them to 36.5 this morning and went out to beat on the tires. Too much traffic to do a good job but I got my pyrometer out and found that the rears might want a little more. This will probably change if I can do some hard launches while hitting the corners. ?‍?

I now have 4,000 miles on the tires and I really, really like them. They are a comfortable tire, even at 41 psi, which is what I have been running them at. As I reported previously, they are a little more slick than the stock OEM tires, but I think that is because they have lower rolling resistance. And I am happy with that trade off. They do feel stickier now that there are some decent miles on them.

The appearance of the tires has grown on me also. Initially I thought the shorter sidewall of the stock OEMs looked better, but now I really like how they look. The difference is definitely subtle anyway, but they look meatier. I especially noticed it when I saw another white GT parked next to me. My car just looked more aggressive, and I think the tires are the main reason why.

Of course, they are a long way from looking as awesome as what Mark puts on his MME.

But highway range is a huge deal for me. I have a long drive to and from my office, and reducing the amount of public charging needed is so important for my stress and well being. I get so angry looking at the charger hogs with their fully charged cars sitting in a charging space when I need a charge to get home. The less I have to deal with those a-holes, the better.

So I highly recommend these tires.

 

[HuntingPudel]

<SNIP>
Of course, they are a long way from looking as awesome as what Mark puts on his MME.
<SNIP>

LOL Mark went down in size, so not as much difference any more. He’s got the same section width I am running. But he’s running 21s to my 20s. ??

 

[mkhuffman]

I updated the OP with the efficiency data. The bottom line: these tires with the larger size are 7.62% more efficient than the OEM setup. Go back to the OP for the full write up and all the data.

 

[Triggerhappy007]

A couple final thoughts:

I think it is possible the larger tires size has contributed to the efficiency improvement. It is a very small difference, but a taller sidewall means the rotational resistance of the wheel has probably decreased at the same GPS speed. So if you replace your OEM tires with the same size tire, you might not see the same improvement I have.

I think this is an incorrect assumption. Wider tires are less efficient. At least, that's what I've been told. Isn't that why the BMW i3 has skinny 155-195 tires?

 

[tuminatr]

I think this is an incorrect assumption. Wider tires are less efficient. At least, that's what I've been told. Isn't that why the BMW i3 has skinny 155-195 tires?

That's mostly true usually the reason why car manufacturers go with skinnier tires is that they can up the pressure. The Mach E is a pretty good example they could have gone with wider tires but wanted to run them at 39 PSI for maximum efficiency.

So the difference in efficiency between a 255 and a 225 is negligible. But the 245 45 20 103 should be run at 39 PSI at 255 45 20 105 should be run at 36 PSI so it would be less efficient

Higher pressure in tires creates less rolling resistance. The pressure is set based on the load rating of the tire and how much pressure is needed to support the weight of the vehicle

 

[Mach1E]

That's mostly true usually the reason why car manufacturers go with skinnier tires is that they can up the pressure. The Mach E is a pretty good example they could have gone with wider tires but wanted to run them at 39 PSI for maximum efficiency.

So the difference in efficiency between a 255 and a 225 is negligible. But the 245 45 20 103 should be run at 39 PSI at 255 45 20 105 should be run at 36 PSI so it would be less efficient

Higher pressure in tires creates less rolling resistance. The pressure is set based on the load rating of the tire and how much pressure is needed to support the weight of the vehicle

It’s not just the pressure that can make a difference.

Wider tires weigh more. And more weight = less efficiency.

We have multiple opposing forces going on in these physics calculations.

 

[tuminatr]

And that's tru

It’s not just the pressure that can make a difference.

Wider tires weigh more. And more weight = less efficiency.

We have multiple opposing forces going on in these physics calculations.

True but 20-30mm makes almost no difference. Or think of it this way width does have an effect but pressure has a much larger effect.

Even there I saw an out of spec range test on the Lucid Air. they underinflated the tires by 7psi and the car went 7 miles less on a charge. This challenged my thoughts on how much air pressure affects efficiency

 

[mkhuffman]

I think this is an incorrect assumption. Wider tires are less efficient. At least, that's what I've been told. Isn't that why the BMW i3 has skinny 155-195 tires?

It is not really an assumption. It is more like a theory.

And that's tru
True but 20-30mm makes almost no difference. Or think of it this way width does have an effect but pressure has a much larger effect.

Except that at 80 mph, rotational air resistance is significant. I think the fact the wheel is spinning 2.6% slower reduces rotational air resistance. At slower speeds the effect decreases and is probably negligible. But I think at 80 mph it is not negligible and contributes to the improved efficiency I measured.

There is no good way to prove it either way. But for sure I am getting better efficiency at 79-80 mph, which is great. It almost offsets my battery's 91% SoH. Almost.

 

[markboris]

It’s not just the pressure that can make a difference.

Wider tires weigh more. And more weight = less efficiency.

We have multiple opposing forces going on in these physics calculations.

Except wider tires do not always weigh more. It all depends on the tire.

For instance, the OEM GTPE summer performance Pirelli P Zero ELECT 245/45/20 weighs 28.1 lbs.

The current tire I am running, the summer performance Michelin Pilot Sport S 5 275/35/21 weighs 27.8 lbs. This tire is 3 sizes wider than the OEM 245's.

 

[Mach1E]

Except wider tires do not always weigh more. It all depends on the tire.

For instance, the OEM GTPE summer performance Pirelli P Zero ELECT 245/45/20 weighs 28.1 lbs.

The current tire I am running, the summer performance Michelin Pilot Sport S 5 275/35/21 weighs 27.8 lbs. This tire is 3 sizes wider than the OEM 245's.

Wider tires always weigh more…… than a skinnier version of the same tire.

Science experiment 101- stick with 1 variable. ?

You not only changed width, you changed wheel size, wheel width, sidewall height and tire brand!

In general, less weight is better for efficiency.

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