Worth it to buy a set of summer tires?

[PandaBear]

Originally Posted By: CapriRacer

Then there is the part about ownng a Prius. If this includes good fuel economy, then summer tires are not a good fit.


I was told previously by someone here or tirerack (forgot who) that summer tire actually has less rolling resistance than all season for the same rating, grade, driving condition, etc.

What is the reason why summer would be better or worse than all season in fuel economy? Is it mainly just a market demand difference or is there actually technical and engineering reason for this?

 

[GC4lunch]

Originally Posted By: PandaBear
Originally Posted By: CapriRacer

Then there is the part about ownng a Prius. If this includes good fuel economy, then summer tires are not a good fit.


I was told previously by someone here or tirerack (forgot who) that summer tire actually has less rolling resistance than all season for the same rating, grade, driving condition, etc.

The target market for all-season tires is, frankly, people whose priorities place longevity ahead of safety. To achieve high treadwear numbers for that market segment, makers of most all-season tires specify the tread compound to be very hard; the trade-off for the reduced wear is a loss of traction, but traction is not the primary selling point for the target market.

However, most all-season tires also are designed with numerous small tread blocks rather than large tread blocks separated by relatively wide channels, and also often are densely siped. The combination of small blocks and dense siping results in energy absorbing tread squirm, which, in turn, adversely affects rolling resistance.

The balance between the reduction in rolling resistance from the hard tread compound and the increase in rolling resistance from the tread squirm varies from tire model to tire model, of course. But I would be surprised if, on average, all-season tires have any overall advantage in rolling resistance over tires with larger tread blocks, greater void-to-block ratios, and softer tread compounds

Originally Posted By: PandaBear
What is the reason why summer would be better or worse than all season in fuel economy? Is it mainly just a market demand difference or is there actually technical and engineering reason for this?

I was wondering the same thing when I read CapriRacer's statement.

 

[CapriRacer]

Originally Posted By: PandaBear
Originally Posted By: CapriRacer

Then there is the part about ownng a Prius. If this includes good fuel economy, then summer tires are not a good fit.


I was told previously by someone here or tirerack (forgot who) that summer tire actually has less rolling resistance than all season for the same rating, grade, driving condition, etc.

What is the reason why summer would be better or worse than all season in fuel economy? Is it mainly just a market demand difference or is there actually technical and engineering reason for this?


There is a technology triangle involving treadwear, traction, and rolling resistance. In order to get improvements in one area, one of the other areas has to be sacrificed - or both.

So what about summer tires? As mentioned, summer tires are geared more towards the traction end of things, so not only is this in direct opposition to rolling resistance, the market segment is smaller than the all season segment, so there isn't as much specialization - and that means tire manufacturers aren't going to produce a summer tire with a low rolling resistance.

Although treadwear is a very important property for the all season tire market, the popularity of all season tires allows tire manufacturers to justify the cost of producing of tires with actual low rolling resistance values (as opposed to tires that give better RR values compared to other tires with similar UTQG ratings and are labled - somewhat falsely - LRR)

The important part here is careful selection.

 

[CapriRacer]

Originally Posted By: GC4lunch
.......The balance between the reduction in rolling resistance from the hard tread compound.....


And just so you know, tires with true low rolling resistance values (not the ones just labled "LRR") are soft - not hard. That's becasue hard rubber compounds generate more internal friction - which is what drives RR.

Many people think that harder rubber compounds affect the overall stiffness of the tire structure and therefore that reduces RR. But most of the tire stiffness comes from inflation pressure - and needless to say, inflation pressure has a HUGE affect on RR.

Also, the steel in tires is much, much stiffer than the rubber, so its affect is larger.

For practical purposes, the rubber in tires hardly affects the structural stiffness at all.

Also, the tread pattern has a pretty small affect on RR compared to the rubber properties of the tread compound. I'm not saying it has no affect, but for practical purposes, you can't look at a tread pattern and judge its RR properties. The tread compund can completely overwhelm any affect tread pattern has.

 

[GC4lunch]

Originally Posted By: CapriRacer

Also, the tread pattern has a pretty small affect on RR compared to the rubber properties of the tread compound. I'm not saying it has no affect, but for practical purposes, you can't look at a tread pattern and judge its RR properties. The tread compund can completely overwhelm any affect tread pattern has.

It is not just rolling resistance as to which your statement is true. Because all tires look like black doughnuts, the advertising agencies who produce copy for tire makers make a really big deal of the one thing that prospective buyers can see, the tread pattern, and build their advertising campaigns around pretty patterns. One of the toughest concepts to get across to Joe SixPack is that the fundamental difference between non-all-season tires (tires that are at their best in 3-1/2 seasons in temperate zones, which often misleadingly are called "summer" tires) and "all season" tires (tires that are at their best only in very light snow conditions) lies almost entirely in the chemical properties of the tread compound and not in the differences in tread pattern.

That said, very small tread blocks, and dense siping, do contribute to tread squirm, and tread squirm never is a good thing.

 

[SteveSRT8]

Originally Posted By: Indydriver
Originally Posted By: rjundi

My qualm and a huge one is even with performance winter tires(which have lessor winter grip than true winter) is they do not offer better dry or wet traction vs an ultra-high performance all-season tire.

I'd like to see you prove this.

The big difference between A/S and winters is that one is designed for 45 and above and the other 45 and below. High perf winters are another compromise but will run circles around your high perf A/S in any condition below 45F.


I maintain summer type tires on two cars as I prefer their characteristics and it is rarely that cold here. No winter only tires here as they are not needed, glad for that!

They are DEFINITELY better in both dry and wet conditions than even expensive all seasons in the same size. Hugely different in cornering, much better in the wet, and slightly better in stopping and launching. But it must be warm to get what they have to give you. Plus my current set is rated at 220 treadwear, and the best I have seen is 300 in a dedicated summer formula. So short life is also the rule here.

I do not like all seasons anymore, once you try a summer only formula you may not want to go back to the reduced levels of traction with all seasons.

 

[CapriRacer]

Originally Posted By: GC4lunch
.........That said, very small tread blocks, and dense siping, do contribute to tread squirm, and tread squirm never is a good thing.


I think you and I are in much agreement - and what I am about to comment on qualifies as "picking at a nit"......

But there is a good thing about tread squirm - and that is wet and snow traction. That bit of squirm helps drive the rubber through the water and snow to the pavement.

 

[otis24]

A lot depends on how many miles you drive. I bought a spare set of rims and put dedicated snow tires on mine. There was a huge difference in handling and traction. With as few miles as i put on my vehicle every year, i expect to get at least four years from a set of winter tires and dramatically extend the life of my summer tires. With two sets of wheels, changing them out will be relatively easy. The fact that you live in South Dakota, not that you drive a Prius, dictates the need for winter tires. Just take a drive over to Chamberlain today and you will see why.

 

[GenSan]

I personally would avoid summer tires unless you only drove on them above 45 degrees F. For your geographic location, at a minimum buy the best all-season tires you can afford. The following video is a great example of how poorly summer tires brake in non-freezing, cold(33-45F) rain vs. winter tires.


If travel to work dictates you need to journey on unplowed roads at odd hours and/or you won't compromise on safety, then ideally have your all-seasons (April-Nov.) plus winter tires (Dec-March) on a 2nd set of rims, and life should be good. This is what my family, in-laws, and extended family prefer.

 

[GC4lunch]

Originally Posted By: GenSan
I personally would avoid summer tires unless you only drove on them above 45 degrees F. For your geographic location, at a minimum buy the best all-season tires you can afford. The following video is a great example of how poorly summer tires brake in non-freezing, cold(33-45F) rain vs. winter tires.


Your video is inapposite. The video showed no all-season tires at all (probably because very, very few all-season tires are sold in Europe). All-season tires would have performed much more poorly than the summer tires in the cold rain; almost every objective comparison test conducted where all-season ties and non-all-season tires are compared and contrasted in wet braking in above-freezing temperatures shows that all-season tires are very inferior in wet conditions -- by design, incidentally, because all-season tires' tread compound is designed to retain moisture on the tread.

Some specialized tires that are designed for high speed driving in hot temperatures (sometimes called Extreme Performance tires, e.g., Yokohama ADVAN Neova) actually need higher temps to get "working": you see race car drivers "scrubbing" their tires with sharp, short turns in the warm-ups for the race in order to get that kind of tire warm. Those specialized tires are not designed for low-speed driving even at room temperature. But the tread compound of most non-all-season tires remains softer at temperatures down to and below freezing than the tread compound of most all-season tires, which is designed for maximum treadlife and generally is harder at all temperatures than the tread compound of non-all-season tires.

For below-freezing winter conditions, winter tires are definitely preferable to any other kind of tire. But all-season tires are not winter tires; the two categories of tires are designed and built entirely differently. An all-season tire is not a junior-league winter tire; it is a different beast altogether than a winter tire.

Originally Posted By: GenSan
If travel to work dictates you need to journey on unplowed roads at odd hours and/or you won't compromise on safety, then ideally have your all-seasons (April-Nov.) plus winter tires (Dec-March) on a 2nd set of rims, and life should be good. This is what my family, in-laws, and extended family prefer.


Here in the Pacific Northwest, and high on a hill, we see wet, cold (high 30s to low 40s F.) conditions in the early mornings (when I do a lot of my driving) half the year.. The last car I bought, factory fitted with all-season tires, I threw out the OEM tires when they had 90+ percent of the tread left, because they were really scary on the wet roads around here. Non-all-season tires are far superior to all-season tires in those conditions. This is the voice of extensive experience speaking.

 

[Rand]

one flaw in your argument.. you are using OEM All seasons which are usually on the wrong side of mediocre at best and biased for high MPG.

and you are over-generalizing way too much.
my factory oem tires had less traction dry than my replacements have in the rain... both of which are all seasons.

Also most summer tires are performance summer tires which means they basically get hard and ""plastic"" like when it approaches freezing.

Also you neglect to differentiate between performance winter and max traction type winter tires.

I would put a good performance winter up against almost any summer tire at 35F

I would put a good all a season tire up against most summer tires at 35F also. Rain, dry whatever.

The key part of the sentence is "a good tire"

In the bigger picture the region obiviously plays a huge role in your tire choice..

If I lived in florida or california. I would most likely have summer tires.

where I live we get 65F in january as well as -5f

we get 80F in september as well as below freezing.

therefore I run a "GOOD" all season tire as well as a dedicated winter for the worst part of winter. mid-nov to end of march.

 

[GC4lunch]

Originally Posted By: Rand
one flaw in your argument.. you are using OEM All seasons which are usually on the wrong side of mediocre at best and biased for high MPG.

I am not using them; I threw them out while they were barely worn. They were Michelin MXM tires, their speed rating was V.

The main thoroughfare on the hill where we live (Portland, Oregon) is SW Vista Avenue, which runs from West Burnside at the north to SW Patton Road about 2/3 or 3/4 of the way up the hill. The first (long) block going southward from Burnside has a pretty fair uphill grade and comes to a traffic light at SW Park Place. You can see it on Google Street View. During the period that we had those Michelin all-season tires on our car, if I had to stop at that light when the pavement was wet, I could not keep from getting some wheel spin when the light turned green and I tried to accelerate from a full stop -- and believe me, I really tried, I did, to keep the wheels from spinning. I never have experienced wheel spin at that intersection when our car was shod with non-all-season tires, even in near-freezing temperatures.

Originally Posted By: Rand
and you are over-generalizing way too much.
my factory oem tires had less traction dry than my replacements have in the rain... both of which are all seasons.

Then your replacements also have poor wet traction.

The problem is inherent in the design of all all-season tires. The natural state of rubber compounds is that they are hydrophobic -- that is, water does not stick to rubber, but naturally runs off. Think of the rain slickers that the traffic cops wear, which usually are rubber-coated. That property is helpful in helping tire treads to evacuate water on the pavement and make an intimate contact between the tire and pavement possible. A famous tire commercial in the 1950s demonstrated that you could actually light a kitchen match on the track a tire makes when it crosses wet pavement.

That same hydrophobic quality, however, is not helpful on snow. The pressure exerted from the mass of the car makes snow melt to water at the molecular level in the contact patch, and a hydrophobic tire can get no traction on the water. So hydrophilic ("water-loving") rubber compounds were invented, and that is the kind of compound used in the treads of all-season tires; it is the employment of hydrophilic tread compounds that enables all-season tires to gain traction on snow. All all-season tires have hydrophilic tread compounds.

Where the pavement is covered with water, not snow, however, you really want the tire to shed the water, not to "love" it. (See the paragraph above starting, "the problem ...") All-season tires love water so much that they pick up water from the pavement, carry it around a full revolution, and still retain a film of water when the same patch again is the contact patch. Result: a water-to-water interface at the contact patch, rather than a rubber-to-asphalt interface at the contact patch. Water is a fair lubricant, and traction suffers.

We rented a crossover SUV at Dallas Ft. Worth International Airport in the spring; of course, it was shod with all-season tires. Just as I got into the car, a spring shower passed through; the shower was over in maybe five minutes, and we had sunshine with wet pavement. There, somewhere between Grapevine and Flower Mound, I made a 90° left turn onto a county road (because of the high center of gravity of the SUV and considerable lean, I slowed 'way down to make the corner), and found myself at the top of a small, not-terribly-steep hill with a stop sign at the bottom, about 75 yards ahead. I coasted halfway down (no need to accelerate, because of the grade) and applied the brakes to stop -- but did not stop short of the sign. Although I assume the modern vehicle had ABS, all four wheels locked, and I slipped and slid right through the intersection; fortunately, there was no cross-traffic. All-season tires.

Originally Posted By: Rand
Also most summer tires are performance summer tires which means they basically get hard and ""plastic"" like when it approaches freezing.

If by "performance" you mean that they are capable of stopping in relatively short distances on wet pavement, yes, most non-all-season tires are "performance" tires. But you are wrong that all non-all-season tires' rubber compounds get hard and "plastic" when temperatures approach freezing. (Yokohama ADVAN Neova and other "Extreme Performance" tires excepted.) In common with all rubber compounds, the compounds in non-all-season tires do get harder at near-freezing temperatures than they are at higher temperatures, but the same is true of the rubber compounds in all-season tires. The compounds of our non-all-season tires (currently, we are running Dunlop SP Sport Maxx TT tires) are softer at moderate ambient temperatures (50s to 90s F.) than the compounds of just about all all-season tires; and as the temperatures go down into the 40s and 30s (F.), the compounds of both the all-season tires and the non-all-season tires get harder, and the compound of our SP Sport Max TT tires remains relatively softer than the rubber compounds of typical all season tires.

Originally Posted By: Rand
Also you neglect to differentiate between performance winter and max traction type winter tires.

When there is snow on the ground just about all winter tires, whether "performance winter" tires or "max traction type winter" tires are superior to just about any all-season tire, and certainly superior to what you call a "summer" tire; I did not "neglect" to make the distinction among types of true winter tires: the distinction is simply of no relevance whatsoever to the discussion we are having here.

Originally Posted By: Rand
I would put a good performance winter up against almost any summer tire at 35F

The temperature you have chosen is a pretty good reference point for discussion. If the temperature is going to stay at 35°, I agree with you that the tires I would prefer to be fitted to my car would be true winter tires. But the temperature rarely hangs around at that level, and it does not take a lot of heat before true winter tires start "chunking" (pieces of the tread breaking off at speed) because, just as non-winter tires' rubber compounds get hard as decreasing temperatures approach freezing, winter tires' softer tread compounds get softer, much softer, as the tires warm up. And most winter tires do not dissipate the heat generated from flexion in high speed driving as well as non-winter tires do.

Originally Posted By: Rand
I would put a good all a season tire up against most summer tires at 35F also. Rain, dry whatever.

And it would lose out in traction tests time after time; such tests have been conducted, and the all-season tire almost always loses. On that same Vista Avenue, farther up the hill, in the S-turn above where Montgomery Drive crosses Vista, on a day the weather was in the 30s and the pavement was wet, I had a new SUV, either Acura or Lexus (I have a hard time keeping them apart) following me; it had been behind me all the way from the traffic light at Park Place, and could not have been going too fast, because he was following me.

In my rear-view mirror, I saw him execute a perfect 360° spin; it was really quite entertaining, in an Olympic figure-skating kind of way. All-season tires, I presume. On my non-all-season tires, I was getting no slip at all.

Originally Posted By: Rand
The key part of the sentence is "a good tire"

Then we are no longer talking about all-season tires.

Originally Posted By: Rand
In the bigger picture the region obiviously plays a huge role in your tire choice..

If I lived in florida or california. I would most likely have summer tires.

where I live we get 65F in january as well as -5f

we get 80F in september as well as below freezing.

There is no tire made that is optimal at both 80°F and below-freezing temperatures, none.

Originally Posted By: Rand
therefore I run a "GOOD" all season tire

Oxymoron alert.

Originally Posted By: Rand
as well as a dedicated winter for the worst part of winter. mid-nov to end of march.

Your choice of tire for November to March is a wise one.

 

[krzyss]

Originally Posted By: GC4lunch

Originally Posted By: Rand
I would put a good performance winter up against almost any summer tire at 35F

The temperature you have chosen is a pretty good reference point for discussion. If the temperature is going to stay at 35°, I agree with you that the tires I would prefer to be fitted to my car would be true winter tires. But the temperature rarely hangs around at that level, and it does not take a lot of heat before true winter tires start "chunking" (pieces of the tread breaking off at speed) because, just as non-winter tires' rubber compounds get hard as decreasing temperatures approach freezing, winter tires' softer tread compounds get softer, much softer, as the tires warm up. And most winter tires do not dissipate the heat generated from flexion in high speed driving as well as non-winter tires do.



I would expect V and H rated performance winter tires to be quite good at dissipating heat with no chunking during highway driving. Racing course (auto-x or track) in high temperature excluded.
Unlike Q and R rated studless tires that may exhibit what you describe.

Krzys

 

[MCompact]

I run summer rubber on the 328i, 318ti, and MS3. The ti doesn't get driven in ice/snow, while the 328i gets Blizzak LM-25s and the MS3 get Cooper Zeon RS-As. The trucks and the '02 run all seasons year-round.
I have a Snap-On aluminum floor jack as well as a Craftsman 3 ton, and perform the change overs myself.