Inflating Winter tyres in Summer

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chrisw said:

First time I've heard of part-new tyres! The difference in fuel consumption will be negligible compared to he other factors such as weather, air con use and traffic, particularly if you are primarily depriving around London. No two journeys are ever the same so comparisons will be difficult anyway.

Just optimism!

Like half-full vs half-empty, we have part-new vs part-worn

Car_54

baser999 said:

Not sure where you get a figure of 55k miles out of a set of all-season tyres? Personally, I’d have not touched those tyres, no idea of their history. Why not buy a proper set of tyres; they’re the only things keeping you on the road, why compromise. 

As I say, just a personal opinion

Indeed.

Fit a few unknown used tyres, pump them up beyond recommended pressure. What could possibly go wrong?

Goudy

chrisw said:

The difference in fuel consumption will be negligible compared to he other factors such as weather, air con use and traffic, particularly if you are primarily depriving around London. No two journeys are ever the same so comparisons will be difficult anyway.

I've ran winters in winter and also winters all year around and tend to agree, mpg differences with winters on will be negligible.

In winter cars tend to be a little less efficient anyway, the quoted 15% reduction is mainly due to the colder temp if you read/believe energy.gov.

Colder oil increases engine friction, it takes longer for the engine to warm up, colder air is denser so increases drag and so on so mpg will drop. You'll suffer all of these whatever tyres you have on.

The actual important thing to consider between winters and summer for economy is the rolling resistance.
The ratio between rolling resistance and increased mpg is actually fairly narrow, though enough over time/mileage it would start stacking up.
Michelin reckon a 30% increase in resistance equals around 5% increase in mpg.

There haven't been many studies between winter and summer tyres when it comes to RR.
There is a Swedish study floating about but I believe they tested Nordic winters (vs summers and studded winters).
Nordic winters aren't the same as normal central European winters, they are much more snow and ice focused tyre.

While there was a difference in RR, there wasn't anywhere near 30% difference in RR between the Nordics and summers on test and speed affected the results as well, summer tend to be better with RR at faster speeds then winters. I guess that's why most winters have a lower speed rating than summers.

Keep them inflated at optimum and you'll be hard pressed to notice on mpg alone.

Your biggest problem using winters all year around is keeping them in good condition for next winter.
As already mention the compounds they are made out of likes the cold conditions, 7c and below.
Warmth doesn't do them much good and they can feel a bit squirmy when they are hotter.
 
Also wearing off the sipes (those tiny wavy lines) tends to lessen the grip when you need it as it's these that grip the ice and snow.
These sipes aren't cut the full depth down to the minimum wear indicators like the normal grooves in tyres, they tend to be fairly shallow.

You get the same sort of sipes on boat shoes, and when they wear off you usually get wet!

Ermia

Goudy said:

chrisw said:

The difference in fuel consumption will be negligible compared to he other factors such as weather, air con use and traffic, particularly if you are primarily depriving around London. No two journeys are ever the same so comparisons will be difficult anyway.

I've ran winters in winter and also winters all year around and tend to agree, mpg differences with winters on will be negligible.

In winter cars tend to be a little less efficient anyway, the quoted 15% reduction is mainly due to the colder temp if you read/believe energy.gov.

Colder oil increases engine friction, it takes longer for the engine to warm up, colder air is denser so increases drag and so on so mpg will drop. You'll suffer all of these whatever tyres you have on.

The actual important thing to consider between winters and summer for economy is the rolling resistance.
The ratio between rolling resistance and increased mpg is actually fairly narrow, though enough over time/mileage it would start stacking up.
Michelin reckon a 30% increase in resistance equals around 5% increase in mpg.

There haven't been many studies between winter and summer tyres when it comes to RR.
There is a Swedish study floating about but I believe they tested Nordic winters (vs summers and studded winters).
Nordic winters aren't the same as normal central European winters, they are much more snow and ice focused tyre.

While there was a difference in RR, there wasn't anywhere near 30% difference in RR between the Nordics and summers on test and speed affected the results as well, summer tend to be better with RR at faster speeds then winters. I guess that's why most winters have a lower speed rating than summers.

Keep them inflated at optimum and you'll be hard pressed to notice on mpg alone.

Your biggest problem using winters all year around is keeping them in good condition for next winter.
As already mention the compounds they are made out of likes the cold conditions, 7c and below.
Warmth doesn't do them much good and they can feel a bit squirmy when they are hotter.
 
Also wearing off the sipes (those tiny wavy lines) tends to lessen the grip when you need it as it's these that grip the ice and snow.
These sipes aren't cut the full depth down to the minimum wear indicators like the normal grooves in tyres, they tend to be fairly shallow.

You get the same sort of sipes on boat shoes, and when they wear off you usually get wet!

Thank you so much! This is very insightful, especially the "30% diff in RR --> 5% diff in MPG" is interesting, so the current tyres are good. I guess wearing off the sipes is also not important either as I don't remember the last time I had to drive on ice in London. 

My conclusion from the discussion is that:

1. It's fine to use winter tyres in London until they wear off. 

2. No need for over-inflating or changing tyres again, as the MPG is only slightly affected by these factors.

3. Having different tyres on the rear axle (one all-season and one winter) could slightly affect handling but in London speeds and careful driving, it would not be felt much. (I haven't noticed anything in the past few days, even when turning in corners, changing lanes, or braking)

born_again

TBH. I would be  avoiding any garage that is selling 3 winter tyre, knowing for well you have summer tyres on the other wheel...
Front drive car, you will get uneven grip if used on there. Rear will also give more grip onside that the other.

You have not mention how much you paid. But it might have been cheaper & more prudent to simply buy a set of budget tyres.

Ermia

born_again said:

TBH. I would be  avoiding any garage that is selling 3 winter tyre, knowing for well you have summer tyres on the other wheel...
Front drive car, you will get uneven grip if used on there. Rear will also give more grip onside that the other.

You have not mention how much you paid. But it might have been cheaper & more prudent to simply buy a set of budget tyres.

Thanks for the advice. Like I said before, part-worn tyres for a 2008 Yaris are around £25 each at most places. New tyres, in comparison, cost at least £55-ish from budget brands. I always replace with another part-new when I get a puncture, as fixing a puncture costs £20, unless the shop doesn't have any in stock.

In all fairness, finding decent part-new tyres is tougher these days, compared to 2-3 years ago. Shops used to have a good stock of them with plenty of tread. Now everyone seems to be on the part-new train, so there's less choice and finding all-seasons with good tread is tricky.  In that sense, even these winter tyres weren't a bad deal.

SiliconChip

born_again said:

TBH. I would be  avoiding any garage that is selling 3 winter tyre, knowing for well you have summer tyres on the other wheel...

I'd also avoid them if they found it acceptable to mix tyre types on an axale, particularly so on the rear axle, where it's generally advised by the industry that the best tyres should be fitted. This is from Uniroyal:

"If you replace old tyres with new tyres and this does not apply to the whole set, there comes the question: Do you fit the new tyres at the front or back? Regardless of the drive type, we recommend not fitting the better tyres at the front, but always fitting them at the back. The reason is simple: The rear axle ensures the tracking stability of a vehicle."

https://www.uniroyal-tyres.com/car/service-knowledge/good-tyres-on-front-or-rear/ 

I'd never fit part worn tyres on any vehicle, but if you're going to do so then it would have made more sense to buy 4 and replace all the existing tyres with the same type.

I'd also suggest that if you're driving is done in London there is absolutely no need for all season tyres, and you can buy a set of decent summer tyres that will work fine for less than the cost of a set of lower standard all seasons.

baser999

Always been intrigued by why people would buy part-worn tyres? They’ve been fitted previously, why did that owner take them off?  Because they were rubbish perhaps? 

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baser999 said:

Always been intrigued by why people would buy part-worn tyres? They’ve been fitted previously, why did that owner take them off?  Because they were rubbish perhaps? 

Possibly.

They could have wrecked one driving over a pothole and fallen for the old (Sucks in between teeth) " You can't fit just one new tyre to that- the difference in grip will destroy the handling and the car will somersault from the road in a ball of flames" ploy.

They might have swapped the set for tyres with more grip (allegedly, manufacturers self-certify anyway), or tyres that are less noisy, or the tyres might have come from a write-off or a car that has been scrapped because the engine blew up.

If they are cheap enough and new enough they are ok, but false economy usually, as they obviously won't last anywhere near as long as new ones, and if you work out mm of useable tread per £ they usually lose out.

Yes you don't know their history, and they could all have hidden internal damage causing them to blow out at speed and make the car somersault over the central reservation in a ball of flames, but so could the tyres on any second hand vehicle, and immediately swapping the tyres for new ones when you purchase a second hand car is pretty rare (but could be another reason for them being at the part-worn shop....) and at least someone has glanced inside these ones unlike the ones that are already fitted.

The main reason for buying part-worns is to save cash now, not everyone can afford brand new tyres.

Also if you are getting rid of the car and just need something legal to pass the MOT, or you are a dealer and the customer complains that a tyre or two are near the limit.......

forgotmyname

Is that chart your actual fuel log?   Not visiting the fuel station to put less than £20 in will probably save more fuel than the
different tyres you can fit.

Are you going to spend 2x to 4x the price of cheap tyres to fit a more fuel efficient tyre?  And don't forget those figures maybe
incorrect for your vehicle weight and tyre pressure.

Yes you can increase and decrease the pressure but then it may wear unevenly and wear out faster so negating the saving
on fuel.