tyre pressures economy??

[chadders1033]

Does anyone use the econ tyre pressure settings on the P3? There are 2 settings at normal load and road speed, 33psi & 38psi to me that's a bit of a difference.

[Rettopian]

I have used the economy pressure setting's which I think are the same as the full load/High speed setting.

Can't say I noticed any economy gains but the ride was a little harsher as might be expected.

I now run with the 'normal' settings all the time.

[Model flyer]

The 38 psi will give a very hard and in my experience a uncomfortable ride and unless the car is very well loaded the tyres will wear quickly in the middle of the tread . Just my opinion others may not find it uncomfortable.

[Sasha94]

I used to set them to 36 and I set the V50's to 36, the big XC didn't seem to mind the pressure, the 50 certainly does! I'm considering lowering the pressure on it, has a really crashy ride that compared to the XC!

[Clan]

Originally Posted by Model flyer

The 38 psi will give a very hard and in my experience a uncomfortable ride and unless the car is very well loaded the tyres will wear quickly in the middle of the tread . Just my opinion others may not find it uncomfortable.

I've found the opposite ! volvos running long term 28 - 30 psi have the edges worn off , usually the inner edges and this is often mistaken for alignment issues , but the alignment is within specification .

I wouldn't say the ride is very hard on ECO settings , The advantages are :
A noticeable reduction in rolling resistance ,
A much more even wear across the whole tread ,
Steering much more responsive, and lighter even with the power steering .
Ride has less wallow .
tyre life longer by as much as 30%
Wet grip is better .

find a piece of smooth level ground , perhaps in a building with a smooth concrete floor , set tyres to 28 psi ... get out and try and push the car ....

Than set the pressures to 36 and 38 psi . do the same experiment , .. Now isn't that just BOUND to save fuel ?

[green van man]

I run mine at 41psi all round at all times, car goes where I point it no drama no fuss, ride is fine, supreamly comfortable, and front tyres lasted 18,000 miles before being changed at 3mm tread depth, not bad for a heavy fwd car pushing near 200bhp through them. Rears I've not yet changed in 3 years of ownership.

Paul.

[Clan]

Originally Posted by green van man

I run mine at 41psi all round at all times, car goes where I point it no drama no fuss, ride is fine, supreamly comfortable, and front tyres lasted 18,000 miles before being changed at 3mm tread depth, not bad for a heavy fwd car pushing near 200bhp through them. Rears I've not yet changed in 3 years of ownership.

Paul.

we should try and spread our secret :-) No one listens though ..

For the last year or so volvos have had tyre pressure monitors , you know what happens ? 2 things :
1 , the light comes on , they take it to the garage because they "don't do tyre pressures" or think there is a problem ..

2: They recalibrate it at the low pressure just to put the light out ..

[tt82]

Used to run them at 38 but I find 35-36 to be a good compromise.

[RoyMacDonald]

Originally Posted by green van man

I run mine at 41psi all round at all times, car goes where I point it no drama no fuss, ride is fine, supreamly comfortable, and front tyres lasted 18,000 miles before being changed at 3mm tread depth, not bad for a heavy fwd car pushing near 200bhp through them. Rears I've not yet changed in 3 years of ownership.

Paul.

Same for me.

JulianT on the v60 forum posted a table of tyre pressure = fuel consumption info. I think it went from about 20 psi to 50 psi. He used near the 50 psi and it made a huge difference to fuel consumption.

The table is here...http://www.volvoforums.org.uk/showpo...95&postcount=3

What made me look at this a few years ago was my monster annual mileage, more than 30,000 a year. So how can I increase my MPG?

Google 'Hypermiling' it's a fascinating topic...but can get a bit extreme.

Drive slow - I can do that, cruise along and take a bit longer to get there

Coasting to a junction - It's amazing how much un needed breaking we do

Tyre pressure - Running at a higher pressure is a classic Hypermiling tactic. Reducing rolling resistance. I tried it and it immediately made a real difference, I could feel the difference.

Web 'evidence' is often just opinion but there is a great US TV show called 'Mythbusters' that does reasonably scientific tests aimed at disproving urban myths. They found (you can watch it here Link) that in this rare case the myth was correct.

These are their results. (not mine)

Control, 35psi (manufacturer recommendation)
tyres at 10psi = 3.7% increase in consumption
tyres at 30psi = 1.2% increase in consumption
tyres at 40psi = 6.2% decrease in consumption
tyres at 60psi = 7.6% decrease in consumption


Car tyres are by the way have to be tested to 100% over pressure. So if your tyre has a 55psi max working pressure it will not deform at that pressure and will have been impact tested at 110psi. The contact area (with the road) must remain within a 5% variance threshold up to the safe working pressure.

So I run my tyres at 50psi. Less than the safe working pressure of 55psi for the current tyre. My view is as long as you stay under the safe working pressure for the tyre, you are fine. That is what a 'safe working' statement is for.

Roy is quite right that the ride is harder for sure, but I run 17' wheels and the ride is still better than it was on 18' wheels.

I don't see a central wear band either, last set on my V50 lasted 50,000 miles and were perfectly evenly worn. I run 225/50/17's.

My V60 and the trusty V50 (best car I ever owned) chug from factory to factory and I inspect safety equipment, the 1.6d e V60 is averaging 69 MPG over it's entire life. That MPG is a mix of things but I'm sure the tyre pressure has a lot to do with it.

When I have mentioned this before some people come back with plausible safety or grip concerns, I have looked into them all before. After 257,000 accident free miles in my V50 and now almost 30,000 miles in my V60 (still prefer the V50) I can say it works just fine.
JulianT

[Finbo]

I tried 38psi on my XC70 (the eco setting) and found the ride quality much poorer than normal, so immediately changed back!