Anyone bother playing around with tyre pressures or just stick to the book?

JethroUK

My Rover 75 should have about 30 psi all around but i put about 34 PSI in to save fuel

The ride is a bit hard, and you need to be bit more careful in wet weather but it rolls down the road like it's on ice and does about 437846728391423678 miles to the gallon

I'll prolly lower the pressures a bit when the ice actually comes

Anyone bother playing around with tyre pressures or just stick to the book?

worried_jim

I do 35psi in my Rover 600.

Yolina

For my Yaris hybrid, Toyota give 2 recommended sets of pressure: "normal" 33psi front/32 rear and "eco" 36 front and 35 rear. So I don't think I need to really do anything more than stick to the "eco" pressure (which is what the tyres were at when I took delivery of the car)

ABN

Was running with 44psi all round, rather than the 32psi manufactures spec.

Found that it gave me uneven tyre wear on the front. Typical of the wear caused by incorrect tracking although the tracking was spot on.

Now running with correct front tyre pressure and 44 at rear which fixed the uneven tyre wear problem.

SailorSam

I think they do a lot of tests to determine the best tyre pressures, i've always gone by the book

Nilrem

SailorSam wrote: »

I think they do a lot of tests to determine the best tyre pressures, i've always gone by the book

Aye and they most likely print the best one for general use.

IE having higher tyre pressures might be better for fuel economy (less contact with the road = less friction), but could lead to problems with grip when it comes to braking, especially in rain or snow (so the higher pressure might be fine in summer, but bad in winter).

forgotmyname

Unless you have different pressures than the book says then go by the book.

34 instead of 30 m,aybe within the limits of the pressure for a fully loaded car??

But if its too high you lose grip as less of the tyre is in contact with the road, And the fuel saving is offset by the extra tyre wear.

So rather pointless. If you replace tyres more often.

waynedance

The makers of my car did all the playing around with tyre pressures and I stick to their findings.

Job done.

waqasahmed

I was going to fill my car with air to the recommended spec (2.3 bar at front, 2.1 bar at rear/34 PSI at front, 31 PSI at rear) but noticed that the Asda machine fills the tyres to the recommended amount automatically?

worried_jim

waqasahmed wrote: »

I was going to fill my car with air to the recommended spec (2.3 bar at front, 2.1 bar at rear/34 PSI at front, 31 PSI at rear) but noticed that the Asda machine fills the tyres to the recommended amount automatically?

How the hell does asda know what car you are driving????

steve-L

waynedance wrote: »

The makers of my car did all the playing around with tyre pressures and I stick to their findings.

Job done.

No they didn't ....(unless your driving the model they determined optimum for and using the same make/model of tyres).....

a) If you look at your recommended tyre pressures you will probably find that they are the same for all models.... the 2L Diesel weighs considerably more than the 1.6 petrol..... they have just got an average. You might have loaded/towing/unloaded for the rear wheels but the same applies to the front as well.

b) Unless you stick with the manufacturers recommended tyres they didn't test YOUR tyres... there is a considerable variation in materials from all weather (not including winter tyres) to track tyres to low rolling resistance eco tyres.
There is as much variability on optimum pressure for your actual tyre as the make/model of car... what is so different between a C5 and Laguna or Mondeo? (All FWD).... the same tyre on each with the same engine weight would likely have a very similar optimum pressure .... In other words the tyre manufacturer has also done a lot of testing on different types of car.... for their particular tyre.

Whenever car manufacturers 'test' they 'initialise' for want of a better word the car. That means track pumps to inflate the tyres exactly for the run they are making. Unless you check your tyres every day/week and top up then likely you lose some pressure in between, I'd say its better to start 2-3 psi high than fall 2-3 psi low.

Tyre compound flexibility changes with temperature, the more towards a track tyre the more it loses flexibility at low temp.
Thus optimum tyre pressure changes from summer to winter.... and motorway to short run....

My car has 3 different wheel sizes (as options) from 17-19 and this changes the profile considerably.... it also (being RWD) has a asymmetric option where the rear tyres are wider than the front.
It has options from a 1.6 petrol to a 3.0 diesel (almost doubling the weight of the car) and only one set of tyre pressures.

It's certainly SAFE to stick to the manufacturers recommendations but it doesn't make it optimum.

It's a separate subject but it never ceases to amaze me how little optimisation manufacturers do! You'd think changing a sticker would be easy but why would they have the same sticker on a C5 in say Saudi Arabia as Siberia?

All in all they tend to produce the car (including stickers) to be sold worldwide in many different conditions..... this means less power/less economy for instance so it meets emissions in say Peru at 15,000' and -10C as well as Israel at -40' and +30C.....
By tuning a turbo diesel's ECU you can still stay WELL WITHIN emissions for a geography and get better MPG.....

Same goes for tyres..... why would the tyre requirements for Saudi Arabia be anything like Siberia? The only place you see a difference though is on very specific workhorse 4x4's (like a HiLux Desert Edition vs Arctic Edition)