Tyre Pressures

[Tigger]

I've got 235/40ZR18's on my W210.

I've also got the Smartire tyre pressure monitoring system installed which I would recommend to anyone not least for never having to get dirty fingers again!

Anyway, in my filler cap the recommended pressures are 29psi for the fronts and 32psi for the rears. I assume these are cold pressures but whats the definition of cold?

Now the summer has gone and things have cooled down I find my front tyres at 25psi first thing in the morning. Should I leave this as it is or should I inflate them to 29psi as per the new cold standard?

As the car settles into operating temperature I end up with my front tyres at 32psi @ 42deg celcius and the rears at 35psi @ 34deg Celcius.

Comments anyone?

PS: I will post some pics tomorrow!

 

[Brian WH]

Cold is defined as before a run, ie. as apart from hot after a run.

Anyway the 25psi is OK but as it is not freezing yet it wouldn't hurt to raise to 29psi in the morning, better to be slightly over than under inflated. The tyre can stand it better and the wear rate will be better.

 

[GregE240]

I've always checked pressures first thing in the morning, do NOT drive before checking them.

I have gone with Brians thoughts of 29 front 32 rear and that has done me just fine. I went through a phase of using the "Komfort" pressures but found the mpg suffered terribly - increased rolling resistance I should imagine.

Get yourself a decent pressure gauge (mine is on my digital compressor, about 20 quid from Hellfrauds), garages vary wildly.

ATB,

Greg

 

[Steve_Perry]

Originally posted by Tigger
...I've also got the Smartire tyre pressure monitoring system installed which I would recommend to anyone not least for never having to get dirty fingers again!...

Silly question, what is this monitoring system and how does it work?

Thanks,

S.

 

[Tigger]

The Smartire sytem involves 4 pressure / temperature sensors that are attached to each wheel using steel bands (like jubilee clips but very long).

This relays pressure and temperature information to the display in the car which means you can monitor them constantly. It will alert you to increases or decreases over definable thresholds but most importantly you never have to crouch by the wheels again!

It has warned my twice already about punctures that I've had. One was just as I was about to join a motorway. It was just a pity that it was a gash in the sidewall so had to get a new tyre.

When you're looking at £150 per corner for tyres you just have to take tyre pressures seriously.

 

[Steve_Perry]

Looks good

Many thanks Tigger!

S.

 

[OGiii]

Re: Re: Tyre Pressures

Originally posted by Steve_Perry
Silly question, what is this monitoring system and how does it work?

It wouldn't have been a silly question if you'd asked how mcuh Steve

So I'll ask.........

Cheers
OG

 

[Tigger]

It costs about £400 and whatever it takes to get it fitted.

Like I said when your tyres are £150 each then it does make a lot of sense.

 

[sym]

Very clever

Seen this on a Renault Laguna as a factory option but heard that it constantly gives false alarms.

How do the sensors attach to the wheels ? I assume they are cordless ? . . . trying to work out how you would attach them inside the tyre otherwise !

S.

 

[RichardM]

Its also a factory option for the W211, but I've also heard it gives constant false readings!

 

[Tigger]

The sensors are indeed cordless and send info to the display unit via radio waves. They attach to the inside of the rim using a long jubilee clip.

In the 18 months that I've had the system I would say I have only had 3 false alerts (high temperature) which I assume are just the result of interference.

Otherwise the pressures shown on the display always tally up with my digital handheld pressure guage.

So on that basis I would say its 99.9% reliable.

 

[clk270]

Friend of mine has similar item on his Laguna as standard (in fact everything is standard including elctric leather chairs, colour dashtop satnav and a splendid Cabasse hifi set up).

As with everything Renault though it does give some false alarms - whilst driving in France in the summer a voice kindly told him he'd lost the two front wheels !!

If you do many motorway or high speed miles then the system is worth having - but if you only do 200 miles a week on urban roads then its cheaper to check them every week.

 

[Dieselman]

Two of my work collgues have Lagunas and neither has any false alarms, but one has tested the system when someone stuck a scalpel through the tyre sidewall at his kids Sunday league footie match.

 

[GrahamC230K]

The gadget Tigger has looks very much like the unit Performance BMW magazine tested on thier M5, back when that was the magazine of my preferance.

They rated it highly. I would have have one if I ever had an extra £400 spare at time of changing my rubber.............but that will never happen.

 

[Kinky]

http://www.tyresave.co.uk/smartire.html

 

[Tigger]

Originally posted by GrahamC230K
They rated it highly. I would have have one if I ever had an extra £400 spare at time of changing my rubber.............but that will never happen.

Hey GrahamC230k,

Never say never mate!