Huge difference in consumption between tires

[69Mach390]

i'm speaking from engineering background and personal experience. saying grippier tires have less rolling resistance does not make sense. everything about them from tire temp, grip, and increased wear indicate the opposite of what you're linking. and lines up exactly with OPs experience.

have you ever switched to summer tires and gotten better fuel efficiency?

It may not make sense, but I trust the data from the tire manufacturers.

There are also plenty of independent studies and actual tire ratings that show the same data:


Summer tires tend to have less rolling resistance vs all seasons or winter tires.

That said, there is so much more involved in tire design than just “summer vs winter.”

I’m speaking in generalities based on the tests and data from the links I posted above from tire manufacturers.

They can design tires for different things, including rolling resistance.

For example, here is a test of a lot of all seasons tires and rolling resistance. A pretty significant difference between the best and worst-
https://www.consumerreports.org/car...tires-can-save-you-money-at-pump-a1547901110/

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[prj]

have you ever switched to summer tires and gotten better fuel efficiency?

Every single year. The consumption is always higher on winter tyres, especially on studded ones.
Consider this also why certain tyres are grippier than others under load:


Of course the drag radials are an extreme example.

 

[RED!]

I’ve read this thread with popcorn, thanks!

as a race car driver who spent decades driving on race tracks 40-50 days a year, I can tell you some things about tires that nobody is really discussing. We measure liters of fuel per minute on track, so this has been the subject of a lot of work by professionals.

1) stickiness is about the tire compound chemically bonding to the rubber in the asphalt road surface, not how soft the tire is but how soft the tread is tires are made of tread, sidewall and bead, three quite different things

2) Rolling resistance is about how stiff the sidewall of the tire is, the deformation of the tire (from circle to oval) increases the rolling resistance (and also adds heat)

3) the width of the contact patch is measured in a few square inches, the wind resistance is a bigger factor from a drag point of view vs the friction from a larger contact patch

3) winter tires are designed to harden at 10 degrees Celsius or less (50F) and are too soft to work properly in higher temps, ie warmer means more rolling resistance since the sidewalls collapse more easily

4) summer tires turn into hockey pucks at low temps, no molecular traction and hard sidewalls, could yield better range but poorer grip for sure

5) all our cars SHOULD be running on the new standard of “HL” which is High Load which is 6-9% stronger sidewalls than XL which are probably the standard when you buy any tire over 280s. This yields lower rolling resistance

my bet is that the OPs summers are XL at best and therefore he’s running ovals instead of circles which take more energy to roll regardless of the tread, treadware, rubber hardness or any other “physics” type argument.

bottom line: Harder sidewalls will provide better range, not necessarily better grip or more fun.

 

[SoccerMan94043]

4) summer tires turn into hockey pucks at low temps, no molecular traction and hard sidewalls, could yield better range but poorer grip for sure

What is the coldest that one can safely use summer tires? I've seen a lot of conflicting information on this.

 

[RED!]

What is the coldest that one can safely use summer tires? I've seen a lot of conflicting information on this.

there’s no set number since every rubber compound is different but the 10c/50F is a good rule of thumb.
Part of the complexity is the temperature of the road surface, your tire pressure (lower means more heat, more heat means higher pressure later since warmer air expands), all of this influenced by speed.

it’s not simple physics since there are a lot of variables. I can tell you stories of cold summer mornings where the track is relatively grippy except in the concrete they put in the high load areas, which is like ice since it cools faster and heats slower. The whole DE day instruction thing of “drive the line” seems like total BS on days like that.

 

[f1eng]

What is the coldest that one can safely use summer tires? I've seen a lot of conflicting information on this.

I change to winter tyres when the ambient drops consistently below 7C and change back to summer tyres when consistently above.
Here in this part of England it rarely snows so winter tyres are probably less suitable than European type all seasons for winter here (North America tyres labeled "all seasons" and European tyres labelled "all seasons" are different for historical reasons) but there aren't any Taycan spec all seasons available here.

 

[ze_shark]

Job #1, 2 & 4 of tyres is to maximize longitudinal & lateral grip in the road conditions they are designed for. EV tyres are therefore a dubious choice given the trade-off with a secondary performance indicator (rolling resistance, therefore range). So are all season tyres btw, mediocre at everything.

These considerations can make the difference between a near miss and a bad accident. Choosing bad tyres to save money or energy is always a questionable decision.

 

[RED!]

Job #1, 2 & 4 of tyres is to maximize longitudinal & lateral grip in the road conditions they are designed for. EV tyres are therefore a dubious choice given the trade-off with a secondary performance indicator (rolling resistance, therefore range). So are all season tyres btw, mediocre at everything.

These considerations can make the difference between a near miss and a bad accident. Choosing bad tyres to save money or energy is always a questionable decision.

I would sort of agree. The truth when you look at the data is generally relatively small except in one area: stopping distance.

I’m a fan of buying stopping distance. I find less lateral grip on a road car isn’t a problem but rather sometimes a pleasure. For example in my NSX, I choose rear tires with a higher treadware rating on purpose because I like the car a little looser in the rear end for fun if driving it, and it allows me to run rear toe without the expensive penalty of needing new tires very regularly.

on the other hand, only serious name brand snow tires since the cheaper Chinese tires have stopping distances that are 15-40% longer and that could save your life or at least my dogs’ from getting hurt and me needing a front bumper. You always want to out-stop the car in front of you in all conditions

 

[cityhpper]

I’ve read this thread with popcorn, thanks!

as a race car driver who spent decades driving on race tracks 40-50 days a year, I can tell you some things about tires that nobody is really discussing. We measure liters of fuel per minute on track, so this has been the subject of a lot of work by professionals.

1) stickiness is about the tire compound chemically bonding to the rubber in the asphalt road surface, not how soft the tire is but how soft the tread is tires are made of tread, sidewall and bead, three quite different things

2) Rolling resistance is about how stiff the sidewall of the tire is, the deformation of the tire (from circle to oval) increases the rolling resistance (and also adds heat)

3) the width of the contact patch is measured in a few square inches, the wind resistance is a bigger factor from a drag point of view vs the friction from a larger contact patch

3) winter tires are designed to harden at 10 degrees Celsius or less (50F) and are too soft to work properly in higher temps, ie warmer means more rolling resistance since the sidewalls collapse more easily

4) summer tires turn into hockey pucks at low temps, no molecular traction and hard sidewalls, could yield better range but poorer grip for sure

5) all our cars SHOULD be running on the new standard of “HL” which is High Load which is 6-9% stronger sidewalls than XL which are probably the standard when you buy any tire over 280s. This yields lower rolling resistance

my bet is that the OPs summers are XL at best and therefore he’s running ovals instead of circles which take more energy to roll regardless of the tread, treadware, rubber hardness or any other “physics” type argument.

bottom line: Harder sidewalls will provide better range, not necessarily better grip or more fun.

Thanks for a very organized and valuable input, @RED!

In the 90's, I drove mid-and long-haul trucks as a way to finance my university studies. I still follow the industry with interest, since in some areas they are more advanced than you might consider: you can now move 60 metric tons and use 3,0 liters of diesel pr 10 kilometers, if the road conditions are good.

Economics means a lot for all hauling companies, and this extends into stuff like tyres. In the Nordics, this has lead to the following procedures: many trucks replace tyres in the early autum. The tread design means that when the tyre is brand new, it has the properties of a wintertyre. As the tyre is worn, a different kind of tread design emerges: sipes are gone and the tread are more similar to a summer tyre. So for the final months of usage of the tyre, it behaves more like a proper summer tyre. Tread dept is much reduced, leading also to less flex and better economy.

This system works well, since the trucks do more than 100 000 km a year. Would have been interesting if tyres could be designed like this for cars that do 20 000 kms a year as well... (yes I know, lots of factors to consider here).

 

[69Mach390]

It took a few months, but I’m glad a few experts joined and backed up what I’ve been saying- that summer tires actually have lower rolling resistance.

Sometimes what you think should be true and what actually is true don’t fully line up.

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