Tyre Pressure

[Bluechaos]

Hi Guys

I am struggling with tyre pressure slightly. I am confused as i have seen a lot of different information as to what tyre pressure i put in and when i read the owners manual i get even more confused.

I believe i still have the factory issue std for my is220d at 205/55/r16/91w

I have been putting 45psi in the front and 48 in the back. problem is i am getting a balding of the tyre on the edge which i believe means there is insufficent pressure in the tyre.

Can anyone heklp or at least point me in the right direction?

Thanks

Ryan

[normski2]

Read the table of size and pressure on the drivers door jamb.

When did you last get geometry checked?

[lexus22]

Good topic, I have the 225's on my car and run 33psi front and 31psi rear, car feels right with this pressure... dunno if it's whats recommended though.

[lexusisfan]

Thanks for bringing up the topic, It would be interesting to see what everyone does.

I'm running 225's at the front and 245's at the back and I use the recommended tyre pressure by Lexus which is definitely not as high as yours.

Also, I've been told that the balding of tyres on the edges means that the tyres are being over inflated, as I'm having the same issue with my tyres.

My local tyre guy has advised me to reduce the pressure to 32 across the four tyres which his signifcantly less than the recommended Lexus pressure, but I'm unsure as I don't want to compromise on safety.

[Bluechaos]

Hmmm this is very intresting, The balding on the tyre may be from a know fault to me but i will have to investigate further the know fault is that the brake calliper pins have seized but have been taken out cleaned and put back in, until i get the pins from the dealer and get my local garage to sort. the car is currently pulling to the left which also happens to be the tyre that is balding on the edge the quickest. I have my mot soon so that will throw up any potential or current issues.

In my limited knowledge I understand the tracking or geometry to be out if the car pulls to one side. I suspect that i will have to replace the tyre to get it through mot but dont want to spend a fortune as i am wanting to upgrade my alloys and tyres to bigger ones but not right this minute.

I have also had a look on the inside of the door and this is where I get the 48 and 45 psi i explained earlier

[normski2]

Then your tyre pressures will be 35 and 38psi assuming you are doing less than 160Km/h.

3rd line down

[johnatg]

Or are you flogging round at 120mph + ??

[lexusisfan]

Or are you flogging round at 120mph + ??

I dont really get who in their perfect mind would be doing 120mph +

Ermmmm...actually had a VW Passat TDI tailgaiting me so had to teach him a lesson....

[Steve_M]

If your tyres are balding around the centre line then they are overinflated, underinflation will tend to scrub the outer edges of the tyres . Normski's spot on with the reccommended pressures for the sizes you quote.

[Bluechaos]

Hi Guys

Thanks for your help, I understand now and it seams so obvious. I will reduce the tyre pressure and I will get the tracking geometry checked when I get two new front tyres I assume will be soon as its MOT time at the end of the month and I don't think will pass MOT in the current state.

Thanks

Ryan

[normski2]

Tyres are so expensive it pays to keep a close eye on them. A quick visual every time you wash your car alerts you to any problems/uneven wear starting to develop.

Check your pressures pretty regularly and get your tracking checked every year...it pays in the long run.

[jayt13]

Agree with normski2 you should be running 35 in the front and 38 at the rear, I tend to check my tyres and pressure every 2 weeks/600 miles.