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tyre pressures

Community Veteran
Posts: 1,229
Thanks: 1
Registered: 30-07-2007

tyre pressures

is it just me, or do newly fitted tyres always lose pressure really quickly for the first week or so, and then "settle down" ?
for instance, I just had a brand new pair of rears on the other day, and within 48 hours they were down 9psi one side and 6psi the other; and this isn't the first time I've experienced this. (mind you I can't guarantee the fitter pumped them up properly in the first place, of course ... )
50 REPLIES
barky
Grafter
Posts: 166
Registered: 21-01-2009

Re: tyre pressures

psi !!  how quaint
could be a few things - slight wheel damage, kids messing about letting air out for fun (never did that myself *cough*), or just a change in temperature causing a slight drop (has got cooler with me the last week or so).
One other thing - my current car (vauxhall) handbook says to check pressure @ warm tyre temperatures -- other have said cold
Community Veteran
Posts: 1,229
Thanks: 1
Registered: 30-07-2007

Re: tyre pressures

mmm yes very "quaint" ... all good general advice of course --  which I could have gathered via google had I not known it all already -- thanks, of course,  ... but my point is a bit more specific, and I really wondered if others had had similar experience with brand new tyres
Community Veteran
Posts: 3,486
Registered: 02-10-2008

Re: tyre pressures

When I've had new tyres fitted usually by Kwik Fit - they have advised checking them again next day when  cold and also check wheel nuts after a few days.
But I don't see why pressure should be lost if they have seated the tyre on the wheel correctly.
They seem to blow up up too hard to do this and then let them down to the correct pressure.
Maybe best go in and ask you tyre dealer what they think.
Community Veteran
Posts: 1,100
Registered: 05-04-2007

Re: tyre pressures

I am going to guess that the problem could be with the valve. Something I have experienced with new tyres. Usually though the tyres have maintained the pressure if the valve is ok.
VileReynard
Seasoned Pro
Posts: 10,583
Thanks: 192
Fixes: 9
Registered: 01-09-2007

Re: tyre pressures

Provided the car is level, I don't touch them - they get re-pressurised at the next service anyway.
What I'd like to know is how can you check the temperature when they are cold, if you have to drive to the garage to check them?

Community Veteran
Posts: 16,834
Thanks: 1,124
Fixes: 13
Registered: 06-11-2007

Re: tyre pressures

Yes... I have experienced that same thing.... I think it depends on the fitter.... as mal0z says some blow them up to about 40psi  and then let them down to the correct pressure....
As I have been in the motor trade, and ran a motorist spares shop, which fitted tyres, I was told to blow the tyres up to about 40psi then let them down, because this put more pressure on the "bead" and seating against the rim. but before we fitted tyres we always gave the inside of the rim (where the old tyre had left some deposits stuck), with a wire brush, and then made sure of the proper seating by immersing the whole wheel in a large tub of water to see if any leaks were apparent, after deflating to the correct pressure, before fitting to the vehicle.
If you are in doubt, remove the wheel, lay it flat on the ground and then pour water around the rim, ensuring a complete circle of water in the crack... also you should check the area around the valve seating with washing up liquid, and put a drop on the top of the valve (valvecap removed) again to make sure that isn`t leaking... (don`t forget to turn the wheel over and do the reverse side too !.
Community Veteran
Posts: 1,229
Thanks: 1
Registered: 30-07-2007

Re: tyre pressures

ta all.
i've noticed this has happened on three different cars with michelins, pirellis and goodyears from about 5 different dealers ... as I say, settles down after a few days so assume the stuff about dirty rims (fnarr) and beading is probably it. I expect they "bed in" after being bounced about for a few days on the potholed rubbish that passes for UK roads these days.
Quote from: Crucibleofevil
Provided the car is level, I don't touch them - they get re-pressurised at the next service anyway.

is that a leg-pull or do you really never check your tyre pressures between services?
@shutter: I'm a man without a garage, or more than a screwdriver in my toolkit, and have to park my car 200 yards from where I live, so if it gets any worse can I just bring it round yours and watch you do it all?  (by the way  -- when i click on the link in your sig it takes me to a directory listing rather than a web page)
Community Veteran
Posts: 6,735
Thanks: 12
Registered: 02-02-2008

Re: tyre pressures

Personally I've never had a pressure drop after a tyre fitting, and I do normally check.
Had a major swap-round (and a puncture repair) on one of my cars the other week and all the pressures are all rock-solid.
Community Veteran
Posts: 3,486
Registered: 02-10-2008

Re: tyre pressures

Community Veteran
Posts: 16,834
Thanks: 1,124
Fixes: 13
Registered: 06-11-2007

Re: tyre pressures

Quote from: paulh
as I say, settles down after a few days so assume the stuff about dirty rims (fnarr) and beading is probably it. I expect they "bed in" after being bounced about for a few days on the potholed rubbish that passes for UK roads these days.
@shutter: I'm a man without a garage, or more than a screwdriver in my toolkit, and have to park my car 200 yards from where I live, so if it gets any worse can I just bring it round yours and watch you do it all?  (by the way  -- when i click on the link in your sig it takes me to a directory listing rather than a web page)

Yes, .... what happens is the tyre flexes as the car is "bumped" around our roads, and the running temp obviously fluctuates with use, and the rubber eventually settles in and seals itself to the rim....
Yes, If you know where I live !... Won`t charge you much !....  you could always take a watering can of water to a nearby layby, or bit of spare ground and do the job, or even do it on a garage forecourt !...  (anyone asks.... "just changing my tyres guv, and checking the pressures")..
Website is "down" at the moment, as I have a problem with the htdocs on the server, I have re-vamped the site, and added a few more piccys, new version has over 1,100 pics on it...  will post a notice on the forum when it is up and running !.
Community Veteran
Posts: 1,229
Thanks: 1
Registered: 30-07-2007

Re: tyre pressures

heheh only kidding  ...  as i could have bought a decent car for about the same price as i paid for the tyres i'll be speaking sharply to the tyre centre rather than trying any DIY, should it  persist ...
Community Veteran
Posts: 18,545
Thanks: 191
Registered: 12-08-2007

Re: tyre pressures

Never used to bother to check my tyre pressures often but then read that fuel consumption can be affected if they are not at the right pressure. I think Ford recommend checking when cold.
Community Veteran
Posts: 16,834
Thanks: 1,124
Fixes: 13
Registered: 06-11-2007

Re: tyre pressures

I think the general consensus about fuel consumption and correct tyre pressures, is you can "waste" as much as 10% if they are incorrect...
10% on a 40 mpg car is only 4 miles per gallon..................................... but hang on a minute....................... how many gallons do you use a month?
(5 galls a week = approx 200 miles) so X 4 for a months fuel .... = 800miles a month.... = 20 galls X 4 ( the 10% wastage) = 80 miles a month    Shocked Embarrassed    or
TWO FREE GALLONS  a month, if you have the correct tyre pressures ! ! ! Cheesy Cheesy Cheesy  (or spending just under a tenner a month too much on fuel )
(assuming I got my maths and the sequence correct !  Embarrassed  )
Community Veteran
Posts: 18,545
Thanks: 191
Registered: 12-08-2007

Re: tyre pressures

Such complicated calculations Smiley  Now where's my slide rule Roll eyes