MK5 Golf GTI
All Things Mk5 => Mk5 General Area => Topic started by: matsu on November 27, 2009, 08:24:02 am
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hi guys
since ive changed the rims to 19s and silly low tyres my dash tells me i now average about22 mpg and it was never below29 before-
is it the actual figure due to less effecient tyres or is it the computer calculating it differently due to the esp light flashing a few times or am i just a numpty not understanding any of this? :ashamed: :sad1:
matsu
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Hi matsu,
Sorry if this is a silly question but have you checked whether you are reading a '1' or '2' value? Meaning whether it's an overall mpg or trip mpg (I forget which is which).
Even if your wheel+tyre combo overall diameter had significantly changed I wouldn't expect mpg to change but possibly mph. But I'm not an expert on this.
Teutonic_Tamer knows a lot about such things but he's not around at the moment.
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Probably due to the heavier wheels.
I've just gone from 17" wheels to replica 18's and my fuel consumption has gone from 36mpg average to 32mpg. Nothing else changed and they're almost all motorway miles.
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Probably due to the heavier wheels.
I've just gone from 17" wheels to replica 18's and my fuel consumption has gone from 36mpg average to 32mpg. Nothing else changed and they're almost all motorway miles.
....So does that mean that by going from 12 Kg Monza'a to 8 Kg Alleggerita's my mpg has improved? :surprised:
In fact my mpg readout has improved but I didn't think it was down to my lighter wheels. I just thought it was a change as none of my journeys are very rarely the same.
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Have you changed the rolling radius of the wheel compared to stock?
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Have you got some Alleggeritas, Robin??? You never mentioned it..... :wink:
Takes a lot of force to get something spinning, and the heavier and bigger diameter it is, the more force it takes. Likewise stopping it again.
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....So does that mean that by going from 12 Kg Monza'a to 8 Kg Alleggerita's my mpg has improved? :surprised:
In fact my mpg readout has improved but I didn't think it was down to my lighter wheels. I just thought it was a change as none of my journeys are very rarely the same.
Possibly, yes.
Most people don't even consider the weight of wheels but it does make a difference for for performance and economy. If your car's trying to turn 4 lumps of lead, it's going to use more fuel than turning 4 biscuits! :grin:
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Matsu - what size tyres are you running as you have changed to 19"s?
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Nice analagy, I assume by biscuits you mean Hob-nobs. As cornering on anything less could be interesting!!!
:laugh:
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Nice analagy, I assume by biscuits you mean Hob-nobs. As cornering on anything less could be interesting!!!
:laugh:
I was actually thinking of rich tea's as they're super-light! :wink:
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Have you got some Alleggeritas, Robin??? You never mentioned it..... :wink:
....Would you like to see pics? And I can also post you a link to my review of them if you like :wink:
I thought it may be useful for those who don't already know the kind of weight differences there are between wheels. Who knows, it could even lead this discussion to calculating that a weight saving of x Kg gives an improvement of y mpg - all approximately of course.
:wink: :drinking:
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Ha ha - Nah, keep it up.
We have a special area of the forum where we play RedRobin Bingo - I've only got to get "Quaiff" before 1pm and I win a speedboat.
And with that leg pulling, I'm off - Cheeky 1/2 track day at Oulton Park is calling... bwaaaapp!
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Matsu,
Take comfort in the fact that I'm on lighter wheels and my average fuel consumption is around 18.7mpg. My current tankful is 115miles travelled and 90 miles left to empty = 205 miles from a tank :surprised:
:ashamed: and :evilgrin: and :driver: in equal measures :signLOL:
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thanks for the input i am running ....the wheels are 19x8.5 et45 and the tyres are falken fk452 215/35zr19
not sure how much diff that is to standard 17 monzas(still for sale plug plug)
my driving is not any different with the exception i,m looking out for potholes and i take corners way steadier due to the flare on the rim with no tyre protection.
also my esp light came on twice but i am very numptynewbie and not sure what i should have done at that stage- does that make the computer calculate differently?
i dont think they are that much heavier to be honest,but thats in laymans terms whist changing them over?!!
hope thats enough new info to find an answer?
thanks again
matsu
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lol hurdy- i,m not actually worried cos i,m velly velly hoppy with my car-and will be even happier by end of jan if my next mods come off,-i just wanna make sure i understand why and if i needed to do anything to her when i changed the wheels-cos i didnt
fanx mate :happy2:
matsu
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In my opinion there is no way just changing the wheels to heavier ones would give 7 miles a gallon less. :chicken:
Surely if this was the case, manufacturers would be making lighter wheels right across the board. 7 miles per gallon would be a lot of engine and fuel development me thinks :smiley:
Just to add my usual caveat though, i could be talking sh*t. :signLOL:
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Thinner wheels/Tyres will reduce drag and help with fuel economy, but I like you TC do not believe lighter wheels would make as much as 7mpg................ :chicken:
The Prius has magnesium wheels but I'd be amazed if they made that much difference. Especially as they then snap on plastic wheel covers which must add weight!! :stupid:
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Not talking s**t TC :happy2:
When I had my 19" CH's on it made about .....zero difference to the fuel consumption :smiley:
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I have also ran 19's and didn't notice a difference. :innocent:
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MY works are 5lbs lighter per wheel than my monza's and my MPG didnt go up. :happy2:
Matsu it's probably coincidence, i would check my DV and get some logs done. :happy2:
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My fuel cons has suffered recently as every morning I am now using....................
Lights
Rear demister
Heated mirrors
A/C on occasion to clear the windscreen
And heater on full tilt
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Thinner wheels/Tyres will reduce drag and help with fuel economy, but I like you TC do not believe lighter wheels would make as much as 7mpg................ :chicken:
The Prius has magnesium wheels but I'd be amazed if they made that much difference. Especially as they then snap on plastic wheel covers which must add weight!! :stupid:
7 mpg is a lot granted, but heavier wheels WILL make a difference. You may not notice it, especially if the wheels/tyres are not much heavier.
It's exactly the same as adding massive heavy brakes, you're adding rolling weight which will hamper performance and increase fuel consumption. By how much is debatable, but it's still a fact.
There are other factors at play here too, like how good your tyres are. I went from Continentals to Sunew's so I can't blame all the mpg los on heavy wheels as my tyres are sh*tE!!
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Thinner wheels/Tyres will reduce drag and help with fuel economy, but I like you TC do not believe lighter wheels would make as much as 7mpg................ :chicken:
The Prius has magnesium wheels but I'd be amazed if they made that much difference. Especially as they then snap on plastic wheel covers which must add weight!! :stupid:
7 mpg is a lot granted, but heavier wheels WILL make a difference. You may not notice it, especially if the wheels/tyres are not much heavier.
It's exactly the same as adding massive heavy brakes, you're adding rolling weight which will hamper performance and increase fuel consumption. By how much is debatable, but it's still a fact.
There are other factors at play here too, like how good your tyres are. I went from Continentals to Sunew's so I can't blame all the mpg los on heavy wheels as my tyres are sh*tE!!
Agreed, but as you have stated there is more than wheel weight to be considered if you have lost 7mpg.
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Agreed, but as you have stated there is more than wheel weight to be considered if you have lost 7mpg.
Very true. I lost 4mpg for which I am splitting the blame between heavy wheels and crap tyres. We'll see how much (if any) I get back when I get decent tyres in the new year
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I agree that any improvement won't be as much as 7 mpg but all the theory points towards some measureable improvement even if it's only 1 or 2 mpg. It's all fairly academic anyway because with lighter and sportier feeling wheels you'll tend to enjoy it more and drive faster, consequently using more fuel!
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It's all fairly academic anyway because with lighter and sportier feeling wheels you'll tend to enjoy it more and drive faster, consequently using more fuel!
Surely that's not true. I thought we all modded our cars to make them more economical and that we concentrated on getting the mpg higher and higher, not the bhp
:rolleye:
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^^^^ :signLOL:
Think ourselves lucky that we don't live in territories where modding cars isn't allowed and we are forced to drive very unexciting cars which comply with draconian rules hiding behind environmental reasoning.
I hate to think what will become of the petrol driven car and am really glad I've experienced nearly 50 years of its development.