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Tyre Pressures

Discussion in 'The Lounge' started by MickLL, Aug 25, 2017.

  1. MickLL

    MickLL Well-Known Member

    I'm not going into detail but I'm puzzled and thought that you might be too.

    I had new tyres fitted on the front of my car and as a result had a "full and frank" discussion with the fitter about the appropriate pressures. I did some research as a result and here's what I found.

    In each case front pressure first and rear second.

    Car sticker 41/41
    Tyre fitter 39/35
    Car manufacturer head office 41/29
    A tyre company website 35/35
    Another tyre co website 41/41
    Dealer Follow the car sticker.

    I'm confused (not too difficult to do these days!)

    Have fun.

  2. Malcolm_Stewart

    Malcolm_Stewart Well-Known Member

    My initial thoughts were - they're high, for a car. I've got used to around 30 - 32 over many years, with perhaps 28 for the rear wheels. Are your tyres super low profile? Would that make a difference, I wonder. The main idea is that your tyre should wear smoothly, and over-high pressures will wear the centre of your tyre, with the edges worn if the pressure is too low. Most importantly from a safety PoV is that your tyres should adhere well to the road.
  3. Bazarchie

    Bazarchie Well-Known Member

    I would go with the car sticker which at least is consistent with one of the other recommendations. Were they all for the same loads?
  4. Footloose

    Footloose Well-Known Member

    I suppose if the car by default comes with one type of tyre, and the manufacturer also offers the option of low profile tyres which require different tyre pressures, (obviously the wheels would also be different so that the tyre diameter remains the same) the labels on the vehicle should provide both sets of pressures? Does the profile of a tyre also impact on the required pressure? I don't know because I don't like low profiles because I worry that the rims will get damaged on things like kerbs and the ride is harder.
  5. GeoffR

    GeoffR Well-Known Member

    I am not sure whether this helps:
    The placard on my car shows three sets of pressures,
    1 to 3 occupants F280 R280 kPa
    Eco 1 to 3 occupants F310 R310 kPa
    Up to 5 occupants and luggage F280 R310 kPa

    Note : Add a zero for hPa or mB (HectoPascals and MilliBars are the same thing)
    In PSI that would be 45psi for 310kPa and 40.5 psi for 280kPa

    In Mick's case 41 may be reasonable depending on the tyre size, mine are 245/40 R19, and vehicle loading. Tyre pressure varies as to required load and manufacturers design footprint. Too much pressure concentrates the footprint to the centre of the tread and causes centre wear, too little and the shoulders wear. In other words, depending on how the car is loaded they could all be right.

    How about giving us the car model and tyre size?
  6. MickLL

    MickLL Well-Known Member

    I tried to keep my initial post simple and so didn't confuse it with loads/tyre sizes etc.

    Yes the sticker on my car gives options for the three possible tyre sizes that can come as OE on the car. Within those groups it gives options for loading.

    You will simply have to trust me that the numbers I quoted are on a like for like basis. i.e for my tyre size and for normal loading.

    My point was the difficulty I had in getting a 'right' answer. Even the manufacturer gave what (to me at least) were crazy numbers 41 psi front and 29 psi rear. I repeat that the sticker says 41/41.

  7. PeteRob

    PeteRob Well-Known Member

    The handbook? That should align with the sticker. I agree the manufacturer numbers look odd, that seems too big a differential - a disporportionate amount of weight would need to be on the front axle.
  8. Terrywoodenpic

    Terrywoodenpic Well-Known Member

    I would speak tho the service manager of the dealership. or chief technician.
  9. dangie

    dangie Senior Knobhead

    How many of us (be honest) adjust our tyre pressures depending on number of passengers and loading.
    I guess very few. If my pressures are between 30-35 psi I'm happy.
  10. DaveM399

    DaveM399 Well-Known Member

    I do about twice a year when the car is loaded up for going on holiday, otherwise I stick to the standard pressures which are for up to three occupants, which are 32F and 29R. The fully loaded figures are 36 F and 41R, glad I've got one of those electric compressors, although the regular minor top ups are done with a foot pump.
  11. GeoffR

    GeoffR Well-Known Member

    In wouldn't they probably have nothing beyond the service Manuals to go on.
  12. GeoffR

    GeoffR Well-Known Member

    Mick, what pressures were you running with the previous tyres? If the wear was even I would just use the same.
  13. Footloose

    Footloose Well-Known Member

    On my car I do the same as Dave, but I also use a wheelchair, which needs a lot more pressure than the garage air pumps deliver, so I use the electric pump in my car for that; It's supposed to be 100psi (!) but I take it up to 90; once the pressure drops to about 60psi, the friction increases and it becomes less easy to self-propel. You can it's reducing because at that point I can 'pinch' in the tyres with my fingers.
  14. daft_biker

    daft_biker Action Man!

    I've always been led to believe the car maker gave the best starting point as whatever is on the tyre is a general guideline and doesn't take into account load or speed.

    Personally I like big, squishy tyres for comfort. 41psi sounds like the economy setup and 35psi might be a bit more comfortable. 29psi in the rear might help grip if it's got a AWD system that only sends drive to the rear when the front wheels slip. I guess they are fairly stiff, large diameter and low profile tyres or is that just the sort of high pressures newer cars run their tyres at?
  15. My experience from my only ever Ford I've owned (never, ever again) was that the car sticker disagreed with the manual, asking the dealer gave a different result, and the head office of Ford UK were too stupid to understand the question. I'd be inclined to go with what the tyre manufacturer recommends for your car, as I imagine they'd actually tested it.

    I had an additional problem with my car, (after I'd eventually found out the correct tyre pressures after two years of ownership) in that when it went in for service, the idiot "technicians" would invariably set the tyre pressures for the petrol version of the car, whereas mine was the rather less common diesel variant. This, if left unchecked, would be likely to lead to a spectacular death at the first bend. The handling of that thing was marginal at best, but with the wrong tyre pressures, it was lethal. it also let the rain in after 18 months. Did you know the Ford warranty doesn't cover it for letting the rain in after a year? Apparently that's acceptable behaviour, and not considered a defect.
  16. SXH

    SXH Well-Known Member

    As in, "it's not a bug, it's a feature"? :rolleyes:
  17. GeoffR

    GeoffR Well-Known Member

    I always thought Ford had some strange ideas, I didn't realise they were that strange!
  18. IvorCamera

    IvorCamera Well-Known Member

    I still have solid tyres on my car, I really must get a new car soon........no only joking, lets be serious....I dont do many miles in my car and if I had to put air in my tyres I would refer to the cars manual which came with the car 9 years ago I have had 2 new tyres on the car since I bought it new 9 years ago it has 27k on the clock, I have a full service by Ford and mot at the same time every 12 months, other than that I would not know the tyre pressures thanks for the reminders.....Now getting off cars I do cycle every so often and I have to put air in my cycle tyres every 6 months and that is just a feel of the thumb on the tyre.....
  19. MickLL

    MickLL Well-Known Member

    Just to answer some comments.

    I did speak to the dealer (see post #1) and their answer was "we always go by the sticker on the door"

    My handbook doesn't say anything at all about tyre pressure other than "go by the sticker on the door". I guess that there are too many model/engine/tyre variants to do it easily.

    The tyre manufacturer (Michelin) won't help. Their answer is , "go by the car manufacturers recommendation".

    Finally the only time I adopt 'full load' pressures is when I drive , with loads of luggage but only two people, to the south of France. I don't bother with a typical UK M'way trip - too short and too slow IMHO.


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