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.
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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.
Are you sure you're interpreting those correctly?Quote:
Originally Posted by chadders
As I understand it, 33psi is for driver and 1 passenger with no luggage. 38psi is for a loaded car, ie driver plus 3/4 ppl and luggage.
The car will not be more economical if you inflate the tyres to a higher pressure than 33psi, nor would it make any sense for a Manufacturer to specify two different pressures for 'driving styles'.
The Economy pressure for Phase 3 is 260kPa or 38 psi. front and rear.
This is from the handbook and door shut.
I run my car on these pressures when doing lots of short local runs where optimum grip is not so important and have noticed less wear on front tyres and slightly better economy. My car is automatic and when driven gently at these pressures even when not loaded everything is fine.
If you drive harder then the front wheels do spin up more often especially in the wet.
Running higher pressures will reduce rolling resistance at the detriment of less grip especially, as you say, in the wet.
My corsa (don't start...) has various tyre pressure settings in the driver info thingy but it basically beeps at me if the pressures aren't within the range of whatever setting you choose.
I've gotta back up what Lee said from recent experience tho...
I've had the corsa on "light load" pressures (31psi front and 29 rear) since I got it but, last week, I upped it to the "eco" setting (38 front, 36 rear) and the handling has been ruined! - Gave it a thrash (as much as you can in the nanny - state new corsa) in the rain the other day and nearly stuffed it into a tree!
My p2 v70 likes 38psi all round in summer, 30 in winter.
Maybe try different pressures until you find something that suits your driving style?
Xc90 is 32 around town / light load or 39 motorway loaded.
I went for 36 and it's ideal for me.
I've gone for 36 all round on the basis that hopefully somewhere in between the two settings will be right for me and the car. Most of the time it's just me in the car doing shortish journeys.
My Corsa?.....:hidesbehiQuote:
Originally Posted by M-R-P
I don't think that statement is true, it could be more economical as rolling resistance is decreased (as per your later comment).Quote:
Originally Posted by LeeT5
Whether I would swap the small gains in economy for the probably more significant reduction in grip, that's a definite no for me...
I know it's not....it's a typo. I've contradicted myself.Quote:
Originally Posted by kmb
Fact is; if you inflate your tyres to higher pressures the car WILL be more economical due to less rolling resistance. However, grip will suffer as the tread compound will not conform to the road surface as well.
There is a tipping point and it's where you strike the balance. It would be almost impossible to work out where that balance was unless you were able to carry out extensive and very expensive testing of the tyre in near perfect conditions, all of the time!
In my R, I have my tyres at 35psi all round. This is for driver and no passengers. I don't care about the economy, if I did, I'd sell it and by a Fiat Panda 750cc or the like. Equally, I don't want the tyres rock hard as the ride is firm enough.
Though It's fair to say an P2R model cannot be compared to a P2T5 as it's a completely different suspension set up and road handling is not the same on any level, therefore having tyre pressures set at 35psi, for example, in both cars would still mean totally different handling and feel.
The bottom line is this, IMHO....
None of this is really worth worrying about. Volvo, as a manufacturer, will have already spent thousands of pounds testing tyres on these cars prior to production and in collaboration with tyre manufacturers.
They will have listed a lower and upper limit that you, as an end user, should be inflating/deflating your car's tyres too in it's daily use. If you stick a roof box on, loaded up the boot with luggage then filled all 5 seats with average weight adults and children and then drove down the M1 at 70mph WITHOUT increasing your tyre pressures to the 'upper' limit, then you'd be increasing the risk of blow outs due to the compression of the weak side wall on your tyres. They will overheat and if in poor condition, cracked, aged UV fatigue etc....more likely to fail.
However, this is less likely to happen if you inflate your tyres to allow for the huge increase in weight in your car.
Let's be clear, I'm not saying you WILL get a blowout, I'm saying the risk of one is increased. By how how much?? Who knows? It all depends on your driving style, types of roads, tyre condition etc, etc.
Equally, If you just drive the car on your own, then the tyres do not need to be inflated so high. To aid more grip whilst maintaining the sidewall strength, a lower tyre pressure is listed. It goes without saying that it would not be advisable to go lower than this limit for obvious reasons. Less control of the steering, more body roll, hotter tyre wall and higher risk of tyre blowout due to sidewall fatigue.
If you have an accident and the fingers pointed at you, tyre pressures are one of the many things checked to see if blame can be pushed in your direction. Incorrectly inflated tyres are a huge factor of road accidents.
So my advice is to stick to the manufacturer's spec and adhere to the pressure listed for a given load, irrespective of fuel economy....which I do not believe comes into it.
If it does, prove me wrong and I'll wind my neck in, but I bet any money you like manufacturers will not list an 'fuel economy tyre pressure' to save you fuel!
It would seem quite odd if they did list an "economy" pressure. Because to me that begs two questions...1) What implications does that have on the oh so controversial economy figures that they tout? ("Hello, is that VW? Yeah, Hi, just wondered how far above normal pressure you pumped the tyres up when you did you MPG calculations") and 2) Are they really going to suggest increasing pressure to improve economy at the expense of grip? That opens a can of worms!
I've seen the two suggested pressure ratings for my Ph2 V70 in the manual and as above they are for normal driving with a light passenger load and higher speed with a higher load. No mention of economy.
OK here is a photo of the tyre pressure plate from a Phase 3 V70
Attachment 31080
As you can see there is an "ECO" pressure.
Interesting. Basically all Volvo is saying is, leave the tyre pressures set to the higher setting, as for a fully loaded car, instead of setting them to a lower pressure for just the driver. Not really an ECO setting, is it!Quote:
Originally Posted by Blackdog
More like, if you can't be arsed to adjust tyre pressures accordingly, leave them set to the higher pressure.
I stick by my original statement. Run higher pressures with an empty car at the detriment of grip, especially in the wet!
AsI stated originally in response to first question.