Tyres, Rolling resistance...

[CBA]

I've put a few extra LBS in my front tyres, an old trick learned... well - each and every vehicle, 2 wheels or 4, powered or not.

I want to go further, but know the grip will suffer exponentially the further I go.

So, low rolling resistance tyres that give traction when needed... these are winter tyres and of a soft compound, worn quite well to higher pressure a few LBS at a time, so flat against the ground, but harder (yes this has sacrificed tyre life, but they cost £30).

What's a good tyre, close to a slick, hard compound, long life, efficient?

[Chris_C]

Probably everything I hate in a tyre will suit you well

I hate ditching a tyre with tread on it and those that have done there best to last forever whilst I've been trying to get rid of them have seemed to be Runway Enduros, Michelin Energys (actually, I used to quite like these and they are always cheap in costco), Avon CR322's and anything Pirelli.

Out of those, I'd only ever drive on the Michelins and Avon's again, both those don't have ridiculously silly amounts of grip but they are hugely progressive and you can feel when they have had enough. I prefer that then something that grips like hell then suddenly lets go. What size tyre are you going for? I'm guessing you are looking 175/70 13s?

[CBA]

yeah, standard size (or even thinner), just for economy -
Something that can go upto 40-50PSI and stay round.

[jtbo]

They use here those nordic stud-less winter tyres for economy driving competitions as those have the lowest rolling resistance.

From 50MPH I can coast better part of a mile on level ground with those.

I'm not seeing logic of adding weight, acceleration will consume more fuel, also to keep same speed you need more energy, even increase is not too great in there.

Michelin Energy is one of the best summer tires here in rolling resistance, but is beaten hands down by these winter tyres.

Probably also reason why I'm getting over 60MPG when there is not too much wind, 45MPG is somewhat typical figure for that vehicle, oh yes, I drive like an old fart

Getting narrow and high profile tyre is not always best option, sidewall flex causes added loss of energy, so there is some compromise for this too.

One way is also to get tyres that have higher load index, so they are bit stiffer, less transformation, less lost energy.

[CBA]

What a product!!!

Thankyou!

[CBA]

Any sources for these actual tyres?

Do they have a more specific name or something, I'm finding the new breed ones only.
Not sure what to search for.

A link to an actual nordic studless winter tyre???

[jtbo]

Continental Viking contact 5, however, how to get them in UK might be problematic/expensive reducing saving to quite small, but still one would get very quiet tire that works very well at winter, but not so much grip than Uniroyals at wet summer I'm afraid.

There is few languages at bottom left at page, but I did not checked if they would ship to UK, price is not bad, 185/60-14 often costs 110€ here, so size in my french crap is one that is in link .
http://www.nordenrengas.fi/Talvirenkaat ... 4_82T.html

Earlier version of tyre was with number 3, it however has only few mm of that grippy good rubber, where in version 5 there is whole thread made of same stuff, which they claim to be first one of the kind where grip and other features stay same until end of thread. In my use tires probably last at least 100 000km based on wear they have had so far. Even people say that you could not drive at summer with these type of tires, there has been no rapid wear or very little grip, which are often claimed to be reasons for fast tyre wear.
Note that previously I had Nokian summer tyres, they had life of 30 000km.

I think that driving style affects quite a bit to fuel consumption too, I got some 50MPG figures before, but as I have altered my driving style I'm getting now around 60MPG figures, wind is quite big effect too so I quite rarely drive past 50MPh, more of I drive smaller roads which have speedlimits of 50MPh.

However at minimum 5MPG improvement I believe.

[jtbo]

I found some data for you, these are from car magazines, they tested rolling resistance multiplier of tyre, smaller is better.

Tested 2004
H-rated 185/65 R15
Nokian Hakkapeliitta Q (Worn northern europe studless winter tyre ): 0,67
Michelin Energy 0,82
Nokian NRHi 0,89
Continental Premium Contact 0,91
Toyo Roadpro R610 0,94
Dunlop Sp Sport 01 0,96
Goodyear Eagle Ventura 0,98
Champiro 65 0,99
Vredestein Hi-Trac 0,99
Firestone Firehawk TZ 200 1,05
Pirelli P6 1,06
Barum Bravuris 1,10
Marangoni Vanto 1,11
Euromaster VH 100 1,24

Tested 2001
195/65/15
Speed rating - T:
Goodyear GT3 0,77
Michelin Energy XT2 0,83
Continental ContiEcoContact EP 0,88
Nokian NRT2 0,95
Pirelli P3000 1,01
Bridgestone B330 1,02

Tires that I have are claimed to be better than those Nokians at rolling resistance, but I don't know, however they are probably best all around tyres I have seen so far. I have heard also rumour that silica compound used in these tyres is the one that does the trick, can't say much about that either, but I know that tires sold at rest of europe are not same rubber what tyres sold here are, ours here are softer compound, which for some reason helps with rolling resistance. Works opposite to my bicycle at least if there is less air in tyre it is harder to keep at speed, but maybe it is then different for the tyre compound

edit:
With Nokian Q 360 would have around 80N (75,6N was wrong) as base rolling resistance force, where with Michelin Energy it would be 98N (that is 1.8kW difference unless I missunderstood my math, but if it is right, then 1.8kW less power is needed to go 50Mph, but I think my conversion from Newtons to kW is lacking), when 360 has quite small frontal area, it has quite small air resistance force even it's Cd is 0.38, for 360 rolling resistance force is then less than air resistance force at 50Mph, air resistance force is maybe 108N, but my frontal area estimate could be wrong, then drivetrain losses (about 22% of engine power, anyone has had chance to measure at uni or rolling road?) and added rolling resistance from speed, which I don't unfortunately have formula in my possession, but for this light vehicle rolling resistance is not increasing very much, you see one odd thing is that weight seem to cause rolling resistance force increase faster with speed.

So air resistance is 108N, then tyre resistance can be 80N to 148.2N depending from tyre, so this would mean that to go 50Mph you need from 188N to 256.2N depending which tyre from the list you have. Now 188N, that is 19.16kg, I guess, maybe it is kilogram-force as those others should be Newton-force as it is force working against movement? Didn't they taught you these cool math things in uni to you, how to make that to be hp/kW/Nm? Also I guess Nm is something that is more than N as 360 has less Nm than 188 for sure Anyway some unit conversions are required to get proper readings, it is noted that 10kW is common number to get car to go 50Mph, so it should be more or less fraction from there what is tyres effect.

Also note that bottom list is not comparable with upper list and only for upper list I have managed to find some reference data.

Some say that rolling resistance is not affected by speed, but it is according to data I found, actually also temperature effects it quite a bit, for each 1C increase there is 1-5% less rolling resistance, when air pressure is kept same.

So if you have wondered why car seem to consume less at sunny days, there is one explanation, also faster engine and box oil warmup play part in there.

10% more rolling resistance when road is wet, so driving only at sunny days will save you quite bit of petrol / increase performance.

edit: I have made few errors, also those numbers are really creations of car magazine, those are just relative values between tyres, however I have found some reference RRC numbers where I did worked out RRC for all these tyres, there are still bit chances of error, but it is hard to find any RRC for exact tyres in this list as even tyre size should be the same, there might be 5-10% of error, I think, maybe, I'm not too sure
There can still be errors in my thinking, especially with unit conversions, but maybe idea is there somewhat.

[CBA]

Defiantly, the air seems "softer" on the warm days, easier to push out of the way...

Those first tyres look very good, I will try to get hold of a set.

I can almost* understand the maths behind it all - Not been to university yet... one more year!

So with super tyres, hard coat wax, global warming and maybe some super slippy bearing grease... lots of more miles per gallon.

[jtbo]

Marine grease is quite nice stuff for bearings, no matter how soaked they will get, that grease just does it's job. That is what I use for bicycle

[CBA]

marine oil aye?
have to look into that...
I always fancied boiling some bearings up in slick 50+motor oil... then running them with a light oil.
Any thoughts on this?

[jtbo]

marine oil aye?
have to look into that...
I always fancied boiling some bearings up in slick 50+motor oil... then running them with a light oil.
Any thoughts on this?

I don't think light oil will stay on place too long, marine grease is kind of axle grease which works much better than normal bearing/axle grease, of course price is tad more which is why automobile industry is not using that too much, often enough good is where they end up to, nobody seeks the best

There is not much one can do to get bearings roll better, just to make sure they are not too tight and that there actually is working grease should be enough.