Whats your MPG?

Mycroft H · 06-11-2012 01:46PM

Slidey wrote: »

Some of the figures being quoted are fanciful at best..

Just a point to note, pumping tyres to max pressure is a dumb thing to do. Firstly, it wears the tyre out quickly. Secondly it gives you a harsher ride and thirdly and most importantly it reduces the footprint of the tyre on the road, in wet conditions this will increase your stopping distance.

It's worth nothing that this is the max pressure on the sidewall of the tyre. The pressure you want is the one on the jamb of the door or in the manual

Amprodude · 06-11-2012 10:17PM

Slidey wrote: »

Some of the figures being quoted are fanciful at best..

Just a point to note, pumping tyres to max pressure is a dumb thing to do. Firstly, it wears the tyre out quickly. Secondly it gives you a harsher ride and thirdly and most importantly it reduces the footprint of the tyre on the road, in wet conditions this will increase your stopping distance.

you will use more fuel when they arent pumped up though.

challengemaster · 06-11-2012 10:19PM

Amprodude wrote: »

you will use more fuel when they arent pumped up though.

And you'll spend a lot more money than what you saved on fuel when you crash

gyppo · 06-11-2012 10:59PM

Citroen C5 Tourer 1.6hdi - 57/58 mpg every tankfull

thecomedian · 06-11-2012 11:33PM

My latest fill up, got me 20.8 mpg
Goes to show it can vary a bit

Cerbera · 07-11-2012 12:19AM

111R - 40

cabb8ge · 07-11-2012 12:39AM

Series 11 Primera (1995), 1.6 petrol, do above 30mpg for me on mix of driving, mainly not stop and start.

Markcheese · 07-11-2012 12:48AM

My wife's 1.4 fabia does about 40 to 45 mpg on general runs, (according to the trip computer) on long runs if the speed is minded it'll do 51 mpg...
Easier to get good milage on ordinary N roads, than on motorways at speed.

Cuddlesworth · 07-11-2012 01:09AM

2005 Forester 2.5xt, 25mpg on a even mix on city and motorway. I could try driving with a lighter foot, but don't think it would be worth it.
2006 Kawasaki Er6n 650cc(motorbike), 65mpg while driving like a asshole.

I drive the bike during the summer to cut down on cost. Don't have much choice in the matter.

BlackWizard · 07-11-2012 01:24AM

That's very good out of that 650cc engine!

I've a Fazer 600cc and get 50mpg driving into town and 55 on motorway. Spirited driving on both.

My Seat Ibiza 1200cc which I haven't started in 4 months usually gets 34mpg all round. Pretty bad for an engine of that size. But cheap tax and insurance and only 1000km a year means I don't care.

N17er · 07-11-2012 02:14AM

Slidey wrote: »

Some of the figures being quoted are fanciful at best..

Just a point to note, pumping tyres to max pressure is a dumb thing to do. Firstly, it wears the tyre out quickly. Secondly it gives you a harsher ride and thirdly and most importantly it reduces the footprint of the tyre on the road, in wet conditions this will increase your stopping distance.

Im sorry but Im afraid I disagree here on two points.

In my opinion, pumping tyres nearer to max sidewall px will result in a more even tread wear, also it will increase the footprint of the tyre in contact with the driving surface resulting in shorter braking distances in most conditions.

It will vastly improve handling on most cars.

You are right on the harshness though and this is the only negative aspect of it.

Not a dumb thing to do at all. After all, this is the manufacturers max safe working pressure and is well within the actual limits of the tyre.

Modern good quality tyres do not bulge in the centre at higher pressures like tyres of the past. Stiffer sidewalls at higher pressures will decrease tyre deflection resulting in more even wear. All this info is freely available on the net.

Imo not pumping your tyres to or near max sidewall is dumb but maybe some people value ride comfort over better handling and fuel and tyre economy.

langdang · 07-11-2012 09:32AM

N17er wrote: »

Im sorry but Im afraid I disagree here on two points.

In my opinion, pumping tyres nearer to max sidewall px will result in a more even tread wear, also it will increase the footprint of the tyre in contact with the driving surface resulting in shorter braking distances in most conditions.

It will vastly improve handling on most cars.

Doubt it.
Might not be noticeable on day to day use on a decent straightish road, but wouldn't fancy it on the average Irish country road. (going on tyre pressure experiments I've done myself - biased toward handling rather than economy) You could live with up to 60kph maybe, but then you'd be THAT langer at the top of the convoy. And most of your savings would be from less drag at that speed, I'd guess.

Shur, by extension - I'd improve the grip, braking and handling of my mountain bike by going from 32psi to 55psi. Not a hope.

Markcheese · 07-11-2012 09:58AM

langdang wrote: »

Doubt it.
Might not be noticeable on day to day use on a decent straightish road, but wouldn't fancy it on the average Irish country road. (going on tyre pressure experiments I've done myself - biased toward handling rather than economy) You could live with up to 60kph maybe, but then you'd be THAT langer at the top of the convoy. And most of your savings would be from less drag at that speed, I'd guess.

Shur, by extension - I'd improve the grip, braking and handling of my mountain bike by going from 32psi to 55psi. Not a hope.

On most country roads you probably shouldn't be doing more than 60 /65 kph anyway.. You can easily do more than that until you come round a bend to meet a tractor and couple of pedestrians trying to use the same bit of road that you need ... Been there, done that ... Too many that was close moments...

Slidey · 07-11-2012 10:04AM

That maximum pressure on your tyre is for when the axle is fully loaded. Check the load rating on your tyre, by law they have to equal or be higher than the maximum weight of your axle so unless you are running overweight your tyre is over inflated. On the rear, in the wet under braking this is a dangerous combination.

langdang · 07-11-2012 10:39AM

Markcheese wrote: »

Been there, done that ... Too many that was close moments...

Try running a more suitable tyre pressure

I can't recall having any of those rounda-a-corner-oh-sheet moments. Probably had one or two (I'm no saint like) but it's so long long now I can't remember them.

I'm tempted to try it for a full tank of petrol, more because I like experiments more than anything else. Must see what the max pressure is on mine.

ARGINITE · 07-11-2012 10:47AM

2006 RX8 - city driving 15 MPG, but on a 100 mile run last weekend I got 22 MPG (the M25 was crawling along at 30 MPH)

renofan · 07-11-2012 10:50AM

1998 Nissan Micra 1.0, last mpg check 2 months ago 52.4 mpg
1997 Laguna 1.8, 41 mpg
2005 Focus II 1.4, approx 40 mpg
1986 BMW 318i, approx 25 mpg
1986 BMW 520i, approx 28 mpg.

Mycroft H · 07-11-2012 11:21AM

N17er wrote: »

Im sorry but Im afraid I disagree here on two points.

In my opinion, pumping tyres nearer to max sidewall px will result in a more even tread wear, also it will increase the footprint of the tyre in contact with the driving surface resulting in shorter braking distances in most conditions.

It will vastly improve handling on most cars.

You are right on the harshness though and this is the only negative aspect of it.

I'm going to need proof to believe that. As far as I know, slidey is right. Sure if it was the case, why do manufacturers just say pump up to max pressure?

Armin_Tamzarian · 07-11-2012 11:30AM

People should really be more careful before dispensing shoddy motoring advice.
The consequences could be fatal.

langdang · 07-11-2012 11:31AM

BX 19 wrote: »

I'm going to need proof to believe that. As far as I know, slidey is right. Sure if it was the case, why do manufacturers just say pump up to max pressure?

Indeed, they are quite happy to specify thinner and lighter oils to increase economy, reduce emissions, so you'd think pumping tyres to max psi would be easier and cheaper than a lot of the tricks they use?

Ronnie Beck · 07-11-2012 04:56PM

N17er wrote: »

In my opinion, pumping tyres nearer to max sidewall px will result in a more even tread wear, also it will increase the footprint of the tyre in contact with the driving surface resulting in shorter braking distances in most conditions.

That sentence is completely wrong on all three points. It increases you MPG by reducing friction. The same friction you use to accelerate and brake. Greater pressure results in greater wear as the tyre has to work harder to maintain grip due to a smaller footprint. It also increases the heat produced when driving, which further increases pressure. This causes the pressure to rise above the max limit which may lead to a blow out.

I know it's only your opinion your giving but it's a dangerous one.

It will vastly improve handling on most cars.

If you want stiffer cornering from your car buy an uprated suspension, don't over inflate your tyres like a tool.

El Kabong! · 07-11-2012 05:31PM

1995 Citroen AX 1.5D non turbo
75MPG every tank measured on actual readings.

Previous car was 1999 Honda Insight
~75MPG every tank, but my best trip reading was 96MPG.

For Forks Sake · 07-11-2012 05:36PM

2011 Golf 2.0TDi

Driving mix: 60% Motorway, 20% N-road, 20% urban, consistent 5.8l/100km and theres over 124k km on it now.

September1 · 07-11-2012 05:36PM

Ronnie Beck wrote: »

That sentence is completely wrong on all three points. It increases you MPG by reducing friction. The same friction you use to accelerate and brake. Greater pressure results in greater wear as the tyre has to work harder to maintain grip due to a smaller footprint. It also increases the heat produced when driving, which further increases pressure. This causes the pressure to rise above the max limit which may lead to a blow out.

I know it's only your opinion your giving but it's a dangerous one.

.

I think you might be confusing static friction that is responsible for traction and higher is better with rolling resistance which increases mpg and lower is better. Static friction is not area dependent in classic physics.

Ronnie Beck · 07-11-2012 05:47PM

September1 wrote: »

I think you might be confusing static friction that is responsible for traction and higher is better with rolling resistance which increases mpg and lower is better. Static friction is not area dependent in classic physics.

I know it's not literally the same friction but I was more just trying to get a point across about road safety without getting all molecular on it.

Ded_Zebra · 07-11-2012 09:55PM

Sorry to disappoint you guys but he is right. On RADIAL tyres pumping them harder increases the print of the tyre of the road but also causes less internal friction within the rubber. This friction within the rubber is what makes a soft tyre hot.

It's all to do with the direction that the belts run in

Slidey · 07-11-2012 10:01PM

El Kabong! wrote: »

1995 Citroen AX 1.5D non turbo
75MPG every tank measured on actual readings.

Previous car was 1999 Honda Insight
~75MPG every tank, but my best trip reading was 96MPG.

I believe you are either crediting a gallon with more than 4.5L or your speedo is highly innaccurate. That or you live at the top of a big hill and only travel one way

Time · 07-11-2012 10:05PM

17.7 mpg was the average i got out of my last full tank. Mostly city driving in a 03 350z, i get around 26mpg on a motorway.

robertxxx · 07-11-2012 10:56PM

72 mpg 1976 triumph spider

Ronnie Beck · 07-11-2012 10:58PM

Ded_Zebra wrote: »

Sorry to disappoint you guys but he is right. On RADIAL tyres pumping them harder increases the print of the tyre of the road but also causes less internal friction within the rubber. This friction within the rubber is what makes a soft tyre hot.

It's all to do with the direction that the belts run in

Tyres have an optimal pressure for grip depending on tyres, car, roads surface etc.. Raising the pressure above this point will decrease grip as will dropping it below. To say that you just inflate them to the max rated pressure on the side to achieve this is ridiculous.

Do you have any links to support this inflate it to the max pressure claim.

Whats your MPG?

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