Uneven PSI in tyres

photome

If the Bridgestones max pressure is 40 psi , it would seem it’s the wrong tyre for your car. Go back tomorrow and see what they say

Scrapit

premiumz said:

AdrianC said:

premiumz said:

We ran over a nail today and it punctured our driver side tyre. Luckily Quickfit had 1 tyre our size left in stock and said they could do it. It was 30 minutes before they closed, so I rushed down there.
It was the only tyre they had but it was a decent one at £305, Bridgestone
The problem is, when I got home I had a look at the tyre pressure as the mechanics don't seem to inflate tyres all the way so you need to do it yourself.
It was 40PSI. My other 3 tyres are 50PSI.
This has me concerned that this tyre will not have equal pressure on the road if the other tyres are slightly bigger?
Is this potentially dangerous?

I assume you mean "the others are slightly harder", not bigger, and they're actually all the same size?
So set all four to the same pressure... Takes a minute. If you don't have a pump, go to the petrol station. I mean, you do check the pressures yourself regularly, right?

50psi is feasible for a Q7, at least the rear, assuming you're usually using it fully laden. But even then it's overinflated for the front.

TBH, it sounds like the tyre place are nearer right here, and at least one of your old ones is over-inflated.

(yours may differ slightly)

In case you're not sure what that's saying, the tyre sizes are in three basic groups.

Lightly laden, the three groups vary:
255/55 18 (unless V rated) and 265/50 19 should be 35 all round.
275/45 20 (Y rated) should be 39 F/35 R.
Anything else, including 255/55 18 V rated and 275/45 20 V rated M+S, should be 38 all round

Fully laden, all should be 44 F, 49 R.

The space-saver spare should be 51.

We drive to France quite a bit. 4 of us and tons of luggage.
So although my three scorpion tyres have a maximum pressure of 50PSI and my new bridgestone tyre has a maximum pressure of 40PSI. I'm not meant to be inflating them to those numbers? Even if I inflated them to a lower PSI. Say, 44. The new tyre cannot go that high as it is 40 PSI maximum. So I would need to inflate that one all the way to 40 to get close to the other three and it still wouldn't be the same.

What should you tyres be inflated to? Not the maximum, what should they be, regardless of what they are, brand etc, what does your handbook /pictogram on the car (as above) state?

photome

Scrapit said:

premiumz said:

AdrianC said:

premiumz said:

We ran over a nail today and it punctured our driver side tyre. Luckily Quickfit had 1 tyre our size left in stock and said they could do it. It was 30 minutes before they closed, so I rushed down there.
It was the only tyre they had but it was a decent one at £305, Bridgestone
The problem is, when I got home I had a look at the tyre pressure as the mechanics don't seem to inflate tyres all the way so you need to do it yourself.
It was 40PSI. My other 3 tyres are 50PSI.
This has me concerned that this tyre will not have equal pressure on the road if the other tyres are slightly bigger?
Is this potentially dangerous?

I assume you mean "the others are slightly harder", not bigger, and they're actually all the same size?
So set all four to the same pressure... Takes a minute. If you don't have a pump, go to the petrol station. I mean, you do check the pressures yourself regularly, right?

50psi is feasible for a Q7, at least the rear, assuming you're usually using it fully laden. But even then it's overinflated for the front.

TBH, it sounds like the tyre place are nearer right here, and at least one of your old ones is over-inflated.

(yours may differ slightly)

In case you're not sure what that's saying, the tyre sizes are in three basic groups.

Lightly laden, the three groups vary:
255/55 18 (unless V rated) and 265/50 19 should be 35 all round.
275/45 20 (Y rated) should be 39 F/35 R.
Anything else, including 255/55 18 V rated and 275/45 20 V rated M+S, should be 38 all round

Fully laden, all should be 44 F, 49 R.

The space-saver spare should be 51.

We drive to France quite a bit. 4 of us and tons of luggage.
So although my three scorpion tyres have a maximum pressure of 50PSI and my new bridgestone tyre has a maximum pressure of 40PSI. I'm not meant to be inflating them to those numbers? Even if I inflated them to a lower PSI. Say, 44. The new tyre cannot go that high as it is 40 PSI maximum. So I would need to inflate that one all the way to 40 to get close to the other three and it still wouldn't be the same.

What should you tyres be inflated to? Not the maximum, what should they be, regardless of what they are, brand etc, what does your handbook /pictogram on the car (as above) state?

Looks like 44 front and 49 rear given the chart that’s been posted and the OP saying he runs it fully laden quite often

if the tyre fitted has a max pressure of 40 then IMO it’s not suitable for the car

Car_54

premiumz said:

AdrianC said:

premiumz said:

We ran over a nail today and it punctured our driver side tyre. Luckily Quickfit had 1 tyre our size left in stock and said they could do it. It was 30 minutes before they closed, so I rushed down there.
It was the only tyre they had but it was a decent one at £305, Bridgestone
The problem is, when I got home I had a look at the tyre pressure as the mechanics don't seem to inflate tyres all the way so you need to do it yourself.
It was 40PSI. My other 3 tyres are 50PSI.
This has me concerned that this tyre will not have equal pressure on the road if the other tyres are slightly bigger?
Is this potentially dangerous?

I assume you mean "the others are slightly harder", not bigger, and they're actually all the same size?
So set all four to the same pressure... Takes a minute. If you don't have a pump, go to the petrol station. I mean, you do check the pressures yourself regularly, right?

50psi is feasible for a Q7, at least the rear, assuming you're usually using it fully laden. But even then it's overinflated for the front.

TBH, it sounds like the tyre place are nearer right here, and at least one of your old ones is over-inflated.

(yours may differ slightly)

In case you're not sure what that's saying, the tyre sizes are in three basic groups.

Lightly laden, the three groups vary:
255/55 18 (unless V rated) and 265/50 19 should be 35 all round.
275/45 20 (Y rated) should be 39 F/35 R.
Anything else, including 255/55 18 V rated and 275/45 20 V rated M+S, should be 38 all round

Fully laden, all should be 44 F, 49 R.

The space-saver spare should be 51.

  my new bridgestone tyre has a maximum pressure of 40PSI.

OP, where does it say that? What exactly does it say?

Scrapit

photome said:

Scrapit said:

premiumz said:

AdrianC said:

premiumz said:

We ran over a nail today and it punctured our driver side tyre. Luckily Quickfit had 1 tyre our size left in stock and said they could do it. It was 30 minutes before they closed, so I rushed down there.
It was the only tyre they had but it was a decent one at £305, Bridgestone
The problem is, when I got home I had a look at the tyre pressure as the mechanics don't seem to inflate tyres all the way so you need to do it yourself.
It was 40PSI. My other 3 tyres are 50PSI.
This has me concerned that this tyre will not have equal pressure on the road if the other tyres are slightly bigger?
Is this potentially dangerous?

I assume you mean "the others are slightly harder", not bigger, and they're actually all the same size?
So set all four to the same pressure... Takes a minute. If you don't have a pump, go to the petrol station. I mean, you do check the pressures yourself regularly, right?

50psi is feasible for a Q7, at least the rear, assuming you're usually using it fully laden. But even then it's overinflated for the front.

TBH, it sounds like the tyre place are nearer right here, and at least one of your old ones is over-inflated.

(yours may differ slightly)

In case you're not sure what that's saying, the tyre sizes are in three basic groups.

Lightly laden, the three groups vary:
255/55 18 (unless V rated) and 265/50 19 should be 35 all round.
275/45 20 (Y rated) should be 39 F/35 R.
Anything else, including 255/55 18 V rated and 275/45 20 V rated M+S, should be 38 all round

Fully laden, all should be 44 F, 49 R.

The space-saver spare should be 51.

We drive to France quite a bit. 4 of us and tons of luggage.
So although my three scorpion tyres have a maximum pressure of 50PSI and my new bridgestone tyre has a maximum pressure of 40PSI. I'm not meant to be inflating them to those numbers? Even if I inflated them to a lower PSI. Say, 44. The new tyre cannot go that high as it is 40 PSI maximum. So I would need to inflate that one all the way to 40 to get close to the other three and it still wouldn't be the same.

What should you tyres be inflated to? Not the maximum, what should they be, regardless of what they are, brand etc, what does your handbook /pictogram on the car (as above) state?

Looks like 44 front and 49 rear given the chart that’s been posted and the OP saying he runs it fully laden quite often

if the tyre fitted has a max pressure of 40 then IMO it’s not suitable for the car

It sounds like a bridgestone tyre that costs a carpet should be a straight replacement for the existing pirrellis, however its looking like it possibly aint. Thats why the OP needs to confirm what their tyres should be, using the chart which will look very similar if not the same as the one Adrian posted to confirm. The maximum is irrelevant if required pressure is below this, and very relevant indeed if required pressure is above this.

AdrianC

premiumz said:

AdrianC said:

TBH, it sounds like the tyre place are nearer right here, and at least one of your old ones is over-inflated.

(yours may differ slightly)

In case you're not sure what that's saying, the tyre sizes are in three basic groups.

Lightly laden, the three groups vary:
255/55 18 (unless V rated) and 265/50 19 should be 35 all round.
275/45 20 (Y rated) should be 39 F/35 R.
Anything else, including 255/55 18 V rated and 275/45 20 V rated M+S, should be 38 all round

Fully laden, all should be 44 F, 49 R.

The space-saver spare should be 51.

We drive to France quite a bit. 4 of us and tons of luggage.
So although my three scorpion tyres have a maximum pressure of 50PSI and my new bridgestone tyre has a maximum pressure of 40PSI. I'm not meant to be inflating them to those numbers? Even if I inflated them to a lower PSI. Say, 44. The new tyre cannot go that high as it is 40 PSI maximum. So I would need to inflate that one all the way to 40 to get close to the other three and it still wouldn't be the same.

OK, so inflate them to the higher-load pressures for those runs, but keep them at the lighter-loaded pressures for more normal use.

No, the "max inflated pressure" on the sidewall is not what you're meant to have them at all the time. It's the absolute maximum they're rated to. But if the Bridgestone has a max of 40psi (sounds low), then they aren't suitable for your car. TBH, I'd be surprised if that is the max - the far-lower-load-rated, much smaller tyres on our daily are 44psi max (actual pressure is 26F/29R). Can you post a pic of what the sidewall actually says?

sweetsand

Hi
You get 2 pressures, one usally with up to three adults the one most cars have and the other is the fully laiden. Indeed the fully laiden is the higher pressure and my feelings are you have yours on the full loaded car and KF has set them at the standard, up to three adults.

But as others stated, check the sides of your tyres, ie the profile, the width and the diamaeter of the tyres and then the speed rating - alternativel check on the kwifit site the numbers on the side of the tyres put them in to get the pressures.

IMO, you may be driving around at the fully laoded pressures all of the time and that affects handling and tyre wear if not fully loaded.
How close is KF to you??

photome

sweetsand said:

Hi
You get 2 pressures, one usally with up to three adults the one most cars have and the other is the fully laiden. Indeed the fully laiden is the higher pressure and my feelings are you have yours on the full loaded car and KF has set them at the standard, up to three adults.

But as others stated, check the sides of your tyres, ie the profile, the width and the diamaeter of the tyres and then the speed rating - alternativel check on the kwifit site the numbers on the side of the tyres put them in to get the pressures.

IMO, you may be driving around at the fully laoded pressures all of the time and that affects handling and tyre wear if not fully loaded.
How close is KF to you??

What has that got to do with the question the OP asked

onlyfoolsandparking

Might help if the OP told us what tyre sizes and profile they are currently running unless I've missed that info somewhere and I too can't see a premium tyre like Bridgestone having a 40PSI maximum.

£305 for a tyre, wow I got 2 RS11,s for less (EDIT: realise this is irrelevant as they are completely different Bridgestones but still shocked by that price!!), sounds like KF haven't done you any favours!    

photome

The tyre pressures are on the chart posted by another poster.

the question in hand is the max pressure of the tyre purchased, and it has already been asked to post a pic of the max pressure for the tyre as it does seem low


I quoted a sweetsand post and this was my reply but it didn’t copy and now sweetsand post has vanished, has he realised he is posting rubbish