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There's a lot of talk of green tyres aiding economy, and many comparative tyre tests include a score for economy. I personally have never found any tyre to have any measurable effect on economy on any car that I have owned. My only thought is that I rarely have 4 tyres of the same type on the car at the same time - having a FWD car means that I am replacing front tyres a lot more frequently. Am I alone, or can any other forum members actually demonstrate from personal experience that tyres make a difference?
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The new tyre information labels have a rating. The Pirellis I have just putback for the wintry season are rated F fairly poor, but I can't say I notice any difference to the C rated Contis I took off. The Contis are a bit wider though so would prob cancel out. I haven't bothered to look up the supposed difference between say A and F. Maybe it isn't much anyway.
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It only makes a deal of difference at speeds which are mostly impossible to sustain for any time on UK roads. The rolling resistance drag goes up exponentially with speed, and makes little difference around town.
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>> It only makes a deal of difference at speeds which are mostly impossible to sustain
>> for any time on UK roads. The rolling resistance drag goes up exponentially with speed,
>> and makes little difference around town.
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I occasionally do a fair amount of long distance travelling on German autobahns, but even then there doesn't seem to be anything in it. Having just fitted a set of 4 Michelins that claim to be green, it will be interesting to see if it makes any difference when I drive to the UK in a few weeks time.
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Inflation pressure is what makes the most difference. I always keep any car's tyres at the high end of the recommended pressure range. Better for sharp responses too.
It's conceivable that hard rubber compounds are freer-running sometimes with an economy effect, and a corresponding loss of grip. But I once got some cheapo Oriental hard-compound tyres and they were rubbish: noisy, lousy grip, and they wore unevenly and quickly. Never again.
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>>Inflation pressure is what makes the most difference.
I don't think so, not with the width and aspect ratio of modern tyres.
ISTR a test that showed little difference in quite large pressure differences. Perhaps due to the relatively high stiffness of the sidewall of modern, lower profile tyres?
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I always thought that fuel-saver tyres made only a small - but measurable - contribution to reducing fuel consumption. I wouldn't expect it to show up on a few tankfuls. It would be more meaningful to measure fuel consumption over the life of the tyres.
Michelin's website has the following:
"Save up to 80 litres of fuel.
Estimate of average saving with Michelin ENERGYTM Saver tyres for petrol vehicles compared to its main European competitors. Rolling resistance tests carried out by TÜV SÜD in 2009 on the 15 key tyre sizes for the European market (MICHELIN was first in 13 sizes and second in 2 sizes). Calculated over the average life span for MICHELIN tyres i.e. 28,000 miles (internal source)."
Considering I'm putting in maybe 50 litres a week for 400-odd miles, that might be 70 x 50 litres over 28,000 miles. Mind you, I have in the past got at least twice Michelin's expected mileage over the life of the tyre, so my savings might be twice as much. I can't give definitive figures.
However, as my last Michelin tyres came with a money-back offer, I don't think I'm doing badly.
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This week just done tyre rotation front to backs and balance for front wheels, the ones on the front are at 4.5mm and now on the rear they have done just 8k & the front ones are on 7mm now which have done about 2k.
The garage gave the waffle about best to rear etc i know there stand on it but i want best to front and good rears for cornering etc.
Tyres are all season Pirelli fourseasons 215/55/16 H rated.
Years back my 155x13 Michelin tyres did me proud at 35k on the front them days are very much over even Michelin changed there compound and they new they lasted too long when the tyre size was altered to show 155 80 13, The only way i can get better mileage is to rotate them as above and i replace mine at 2mm if i get 14k i'll be lucky.
Pressure is 32 psi & wheel alignment been done front and rear no unusual wear issues just tyre compounds are not as tough as before.
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I find cheaper tyres to be more economical.
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The effects of make of tyre on economy is minuscule, and the benefits could never be accessed by the average driver doing average driving.
How you drive the car has the most significant effect on economy, you don't need special tyres for that
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>>The rolling resistance drag goes up exponentially with speed
Aerodynamic drag force does increase with the square of speed, and so, at high speed, it dominates over the tyre's rolling resistance.
So, if you are looking for driving conditions which will show up the difference between tyres, it is low speed usage, where the drag from the tyres is comparable with the aerdynamic drag.
At higher speeds, the rolling resistance of tyres does increase, but, it's a weak, linear, effect.
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>>The effects of make of tyre on economy is minuscule, and the benefits could never be accessed by the average driver doing average driving. <<
Based on Mike H figures (using the Michelin'upto' figure) above I think that would give a saving somewhere between 1 and 3 % .
That will be easily lost in the local variations occuring in a measurement over only a few tankfuls. However it may justify paying the premium for Michelins over some other makes.
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To put some figures against my vague statements above...
For a mk4 Astra 1600 on a level road
Below 5 mph the tyre rolling resistance accounts for over 99% of the total drag power
below 20 mph, the tyre accounts for over 90% of the drag power
below 30 mph, the tyre accounts for over 80% of the drag power
At the vehicle's top speed, 112mph, the tyre accounts for 28% of the total drag power
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I doubt efficient tyres would make much difference to the fuel economy of the majority of drivers, blasting up to every junction and braking at the last minute as most seem to do sees the car under power almost constantly.
Those who have mastered pulse and glide could i suspect make good use of the better rolling resistance by gliding more and pulsing less, its the overrun thats free so every extra yard is a saving.
I probably should but don't run my tyres at higher pressure, have them at the correct setting for load and speed as recommended by the maker, two reasons, more tyre on road (debatable as to better wet grip no doubt) and slightly softer ride.
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That's a bit of a surprise to me N_C. I always thought tyre drag was even less than that, but since the average speed of a car is probably around 30mph taking into account town and out-of-town driving tyre drag is maybe more important that I gave credit.
Our FRV regularly averages 34-36mpg now on Michelin Energys, compared to 32-34mpg on the previous Bridgestones (plus one Nexen CP461 that was on it when I bought it).
The car wore the Bridgestones to 20,000 miles (renewed all 4 despite the rears being part-worn as Costco had a 4 for 3 offer on), and is now on 42,000 (fronts at 4mm).
The small improvement may of course be due to a more run-in car, or even Honda using a thinner oil (0W30 vs 10W40) to previously.
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>>That's a bit of a surprise to me N_C.
Yes, I agree - I had expected the tyre drag as a proportion of the total to drop off more quickly with respect to speed than it did in this case.
However, I can imagine that over the life of the tyres, if low rolling resistance tyres give a 2, maybe 3% improvement in rolling resistance drag, they would save enough fuel to buy the tyres in the first place.
As mentioned above, inflation is an important factor, as is correct wheel alignment.
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With manufacturers doing everything possible to get a car into a lower taxation class - even a 2% saving from an ecotyre will be worth having. Hence some cars being supplied with the ecotyres I guess for 'taxation class approval' reasons.
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On our Bravo we had Goodyear Efficient grips, and they lasted 30k miles on the front at an average of 50mpg.
Got a set of Bridgestones on and the next day the consumption dropped to 45. They also lasted only 8k miles - same driver, same roads, same conditions.
On telling tyre retailer they said they could send them back but they would just claim they had been abused so we didnt...
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Prius Chat forum (US) is full of owners seeking more efficient tyres. Quoted losses due to higher rolling resistance are around 5-7mpg...
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We are talking numbers of in excess of 10% there. I would state that the owners are lying.
Edit, no lets be kind - Exaggerating.
Last edited by: Zero on Wed 31 Oct 12 at 07:11
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It's possibly true.
The difference in energy wasted by a very low rolling resistance tyre and a crap one is >30%.
Assuming the Prius is running about at 25-30mph I reckon they could see ao 10%+ difference.
I do, however, take many mpg fantasist claims with a big pinch of salt (>6 grams).
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>> It's possibly true.
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>> The difference in energy wasted by a very low rolling resistance tyre and a crap
>> one is >30%.
30% Really? If that were the case *every* car would be fitted with them to met any of the imposed government targets on emissions. Londons congestion charging income would collapse.
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That's 30% of a fraction of the total energy required for a car of course.
Doesn't affect pumping losses, aerodynamic drag, geartrain drag, etc.
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>> ............ a big pinch of salt (>6 grams).
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Assuming a specific gravity of 2.165, then 6 grams is a reasonable size pinch of salt.
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a big pinch of salt (>6 grams).
is that not about the RDA?
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In cookery terms apparently a pinch is equal to two smidgens or half a dash.
www.amazon.com/Pinch-Dash-Smidgen-Measuring-Spoons/dp/B000E8OPVS
Last edited by: CGNorwich on Wed 31 Oct 12 at 09:04
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>> www.amazon.com/Pinch-Dash-Smidgen-Measuring-Spoons/dp/B000E8OPVS
>>
Well, I'll be a monkey's uncle ~ if I wasn't a snail, that is!
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Most people I have seen buying tyres buy in following methods
1) Newish car - 2 or 4 x same as originals
2) Fit 2 x of the cheapest tyres where they recognise the brand name
3) Fit 2 x of the cheapest tyres
4)Older cars - Do you have any 2nd/part worn?
I do not know anyone that goes into the finer points of rolling resistance, tread patterns, asymmetric treads etc etc.
I know a few who buy Michelins because they do tend to last longer and/ or they are on a Special @ Costco.
What category do you fall into? or make your own category.
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Always 1, irrespective of age of car, and obsess for days beforehand about rolling resistance, wear rate, tread patterns and so forth. Then spend more days trying to get best price and wishing I had a life.
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I'm always in category one regardless of the age of the car, and I buy the tyres from the most convenient place.
Last edited by: L'escargot on Wed 31 Oct 12 at 09:48
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>> I'm always in category one regardless of the age of the car, and I buy
>> the tyres from the most convenient place.
I am in 1, buy my tyres in pairs, choice based on the characteristics I want*, purchased by a combination of price/convenience.
Currently really pleased by the uniroyal rain thingies, will stick with them..
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My own car usually doesn't need new tyres by the time I change it, as I'm only doing 5-6,000 miles/yr.
The family wagon gets Michelins from Costco as per the special offer.
I've been very impressed with the Latitude Tour on the CRV, and the Energy on the FRV in their all round ability and durability.
Previous Energy (?3A) tyres on my old Civic (before we had a 2nd car as we had nae bairns) were gash in the wet so I used the Pilot Sports thereafter (20-25k miles/fronts was the norm despite plenty of VTEC yo') - current Energy ones on the FRV are excellent in the wet.
Without the Costco deals, I'd probably go with the Rain Experts from the number of good reviews they gather.
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The BMW came with Michelin Energys all round in EfficientDynamics trim. They are so lousy in the wet I can't believe they are legal. I doubt a set of LingLong Golden Grip Super Star Pluses would be significantly worse in damp conditions. Which is a shame, because I believe these tyres are specific to this model, so are likely to be replaced like for like when worn.
The Golf gets whatever brand name stuff is on offer at the time. Currently wearing Firestones. Before that, Pirelli.
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I fitted Michelin Energy on the Yaris in 2010 and drove through snow in the next two winters with no problems...
Looking at the tread, they should do 40k miles +.
The Jazz is on the later design Michelin Energy..
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More discussion on the new European tyre labelling regulations here.
www.bbc.co.uk/news/business-18870978
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20% off Michelins at Costco for next 3 weeks - 5th -25th November
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My C5 was said only to make its claimed eco figures when fitted with the original Michelins. However I wanted a different performance/cost balance so swapped for Vredestein Sportrac 3. MPG not noticeably reduced.
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@ the OP. Tend to agree in a laymans sort of a way. I have done a lot of miles over the years in cars which have by default had lots of different tyres on them and while, admittedly subjectively, I think I've been able to sense differing levels of grip or noise, I can't say I could substantively say there was any noticeable difference in fuel economy. I do keep pedantically detailed records of fuel usage as an aside. Some do seem to wear better but might conversely be accused of worse grip. That factor being most apparent in the wet, maybe obviously.
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Effect of tyres on economy - Manatee
