32 psi seems soft

[Habu]

I know tyre and car manufacturers spend huge amounts of time working out the optimal tyre pressures for our cars but, if I’m reading the b-pillar plaque correctly, 32 psi for an NX running on 18’s doesn’t sound like a lot especially given its weight.  The only reason I query this is doing something like a 3-point turn the steering is heavy although it feels fine on the move.  My previous car, a Kia Sportage of similar weight was 36 all round whereas the wife’s small Mazda CX-3 is 33 (f) and 30 (r).

I presume everyone here is running on 32 all round?

cheers

Peter

[Herbie]

It doesn't really matter what we think, what we feel, or what we want our tyre pressures to be - if they aren't what the manual states they should be and you're in an accident, your insurance may use it as a way of getting out of their responsibilities.

I think someone on these forums posted as much about a year ago. He cited the case of a friend of his who was running a different pressure all round from what the manual stated and he said that the insurance either lowered the payout or refused to pay out altogether.

I've seen all sorts of reasons for messing about with tyre pressure (harsher ride/softer ride/better mpg etc) but it's one thing I just won't mess with - my pressures are what it says in the manual/on the pillar.

[Habu]

I wasn’t suggesting I was going to ‘mess around with them’, it was more a case of being surprised the optimal pressure was a lowish 2.2 bar (32 psi) for all 4 tyres.  But I do entirely agree with what you say in general about changing pressures for perceived better mpg or grip, etc. I’ve always stuck to the recommendated pressure, I’ve just not had a car a low as 32 psi for a long time.

50 minutes ago, Herbie said:

It doesn't really matter what we think, what we feel, or what we want our tyre pressures to be - if they aren't what the manual states they should be and you're in an accident, your insurance may use it as a way of getting out of their responsibilities.

I think someone on these forums posted as much about a year ago. He cited the case of a friend of his who was running a different pressure all round from what the manual stated and he said that the insurance either lowered the payout or refused to pay out altogether.

I've seen all sorts of reasons for messing about with tyre pressure (harsher ride/softer ride/better mpg etc) but it's one thing I just won't mess with - my pressures are what it says in the manual/on the pillar.

 

[rayaans]

49 minutes ago, Herbie said:

It doesn't really matter what we think, what we feel, or what we want our tyre pressures to be - if they aren't what the manual states they should be and you're in an accident, your insurance may use it as a way of getting out of their responsibilities.

I think someone on these forums posted as much about a year ago. He cited the case of a friend of his who was running a different pressure all round from what the manual stated and he said that the insurance either lowered the payout or refused to pay out altogether.

I've seen all sorts of reasons for messing about with tyre pressure (harsher ride/softer ride/better mpg etc) but it's one thing I just won't mess with - my pressures are what it says in the manual/on the pillar.

Thats not particularly true. 

Some tyre companies (National Tyes) recommend inflating 10psi over manufacturer recommended levels as tyre pressures vary between 4-8 psi on any normal journey. 

Tyre pressures also vary depending on which wheels are turned, how much load the car has inside etc 

Insurance companies cannot directly measure this because in some cases, cars are levelled differently if there is an incident etc. 

My RX is pumped up to 36psi. Its recommended at 32psi.  They are recommendations, not the law. 

[NemesisUK]

Tyre pressures are derived from the axle weight and contact patch area.

Under inflation will allow the tyre to flex excessively and potentially over heat.

Over inflation is less concerning, some police pursuit drivers will inflate their tyres to the max permissable to give pin sharp handling, at the expense of ride and a reduced contact patch area.

Generally, for normal day to day driving, it is always better to stick with the manufacturer recommended pressures and especially any front rear delta. 

The pressures are recommended for a reason, not simply plucked from the air....

[Guest]

... the insurance worry is nonsensical. It would require everyone have calibrated gauges for full compliance.

Just 1 psi can feel different so it's worth experimenting within reason.

You will find there is a second set of pressures for loading or anticipated high speed. So you can easily use those higher pressures at least.



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[Glover]

Gen3 RX450 is 33 all round but 36 Eco and higher still for more passengers and speeds in excess of 100mph; so there appears to be some flexibility in pressures