GeoffPFC

I have the 21 inch wheels and the label on the filler cap flap says that the front tyres should be at 44 psi and the rear at 49 psi !!!

My tyre specialist says that they recommend 35 psi all round and the Tyre technician at my local Audi main dealer says 38 psi all round!!

I think that I'll go with Audi and see what happens!

Hasser

does it not depend on the tyre as well?

all tyres will have max inflation pressure stamped on.

i have the 21 inch wheels with pirelli p-zero tyres - they say max inflation is 55 psi.

but i run all 4 tyres at 45 psi

24wheeler

The maximum inflation pressure on the tire is the maximum safe pressure allowed to seat it during mounting on the rim. Any more and the risk is that it will pop off the rim and explode rather than pop across the seat to meet the rim as it should. Lubrication is generally used to help.

The tire pressure for the appropriate size is on the body sticker. I have found that the fully loaded pressure is the minimum suitable for my car and tire life is greatly extended if two or three psi above this is used when the car is actually loaded with five or more people and/or luggage. Mine are set at about 45psi all around.

Jusforfun

Anything in the 30s is too low for a Q7! the 44/49 is actually correct though many of us run our cars at lower pressure as a personal preference.
Over the years and many discussions where shoulder wear has been an issue I have noted through spreadsheet (updates) that most people who ran at lower pressures increased pressure for next set.
44/49 sounds high to car users but anyone used to vehicles over two tons will be used to using these pressures.
Basically it is not an error, run in hte 30s you will get shoulder wear and drifty cornering anything in the 40s will be a significant benefit in both wear and performance. It is even more important on the 21" rims.
Worth noting that 24wheeler is on 18s which do have a slightly lower recommended pressure.

24wheeler

It is also very important to only use tyres suitable for 'extra load' on this car. This is indicated on the side of the tyre and on the tyre specification by 'XL' following the size. 44/49psi is the fully loaded pressure recommendation.
It has come back from the Audi dealer twice with the pressure lowered from my 45 to 47psi to a ridiculously low and not-recommended 35psi. Dealer's workshops are pretty useless as a rule I'm afraid.

Actually my size is 255/55r18 which have exactly the same pressure recommendation as even the 21". The slightly lower pressure is for 235/75r18 tyres.

ercstar

Previously I used exclusively 40+ on my first set of 21' (fully loaded or not) and noted after changing them that there was greater wear in the middle of the tire.

Im currently running 38 on my second set and they too appear to be running a little thinner in the middle, which leads me to believe 36 is probably spot on for my typical usage.

Having said that, I do run alot of motorway miles at healthy speeds so I shy away from lowering the pressures any more. Furthermore, if you really load up the car, it makes sense to pump them up to 40+.

Reggie

The fed gov has now changed the pressures posted on the stickers for cars. It now only shows pressures for a fully loaded car.

Look in the manual to find the correct pressures that Audi recommends for your vehicles. I tend to run the min pressure +2lbs

GeoffPFC

Hi Guys

Many thanks for the replies, I have spoken to Audi UK head office and they say that the 21" wheels are not an approved fit in the UK even though they are supplied with the car!

The tech guy did agree that running "unloaded", the pressure would be better in the 40+ range, as they are conscious of tyres wearing out prematurely due to excessive shoulder wear.

I am now running them on 40 psi as there is only 2 people in the car most of the time and I'll monitor the wear patterns.

Best regards

Geoff

djc1969

My 2011 3.0Tdi S line on 21's came back from the dealer following a service on Saturday - with a note that they had REDUCED the tyre pressures to 38psi all round! Seems they haven't a clue what pressure they should be using!