Tyre pressures - check them!

[M1tchy]

Well I picked my A7 up about 8 months ago now and had very few problems. I've got pretty much every option going but the tyre pressure monitoring system seems to be a bit behind the times. My last car was an insignia (or inshitnia as it became known) and on the display showed the exact PSI of each wheel.

The Audi system relies on being told the pressures are correct and then looks for any difference in wheel speed due to under or over inflation.

Anyway, I've stupidly never checked the pressures on the A7 since taking delivery as I've assumed if there was a fault the system would pick it up and alert me. After finding my foot pump following a garage clear out I thought I'd check them - and they were all wildly off! They were so wrong I not only used the gauge on the pump but double checked with a TPG. Turns out the front left was 17 PSI out and the others were between 5 and 15 PSI out. I am gob smacked that the TPMS hasn't picked this up.

Got a 300 mile trip on Thursday night so hopefully they have been this way since I've had it and I can smash my previous mpg best of 46.

All sorts of things going on in my head now. How long have they been like this? Does the TPMS system work? How much have my tyres worn because if this? What effect on my MPG? Should Audi have picked this up on its numerous trips into the dealer?

Either way it's my fault for not checking but I only stopped doing it regularly as it has TPMS.

Well that post turned out to be longer than expected! All I was trying to say is check your tyre pressures lol!

[shabazmo]

M1tchy, I have TPMS and have been grateful as it has alerted me to 3 punctures in 3 years which would have cost me new tyres if I had not stopped in time. I reckon you loose anout 1.5 to 2 psi every month, so monthly checks are a must. I think its 25psi on the fronts and 30 on the rears are the correct pressures. Remember to reset your TPMS when you put air into the tyres.

[Moogie]

25 front and 30 rear sounds a bit low. The correct pressures are on a label on the edge of the drivers door.

without going out to check, I'm sure the fronts are set higher than the rear, and are something like 38 psi and 33, but depends on wheel, tyre size and load.

[shabazmo]

OOPS! typo error. Should be 35psi at the fronts.

[M1tchy]

I think mine were 44 at the front and 38 at the back? Will double check tomorrow.


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[M1tchy]

Well with my pressures correct I averaged 47.1 mpg on a 301 mile trip. Aircon on the whole way, fully laiden car and boot and doing 80mph where possible on the motorways.

Really happy with that!


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[M1tchy]

P.S. These are the correct pressures for the A7:

http://i1009.photobucket.com/albums/af211/mitchy1408/951627EF-9CF0-4BED-ABBE-C91598C2CF9D_zpsztynakzr.jpg (http://s1009.photobucket.com/user/mitchy1408/media/951627EF-9CF0-4BED-ABBE-C91598C2CF9D_zpsztynakzr.jpg.html)


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[K3ITH]

Tyre Pressures checked. They were out by a small amount.

I have 275/30 R21's - I was surprised at the spec - 35psi rear -41psi front

[shabazmo]

Well, I checked again and my A7 says 35psi on the fronts and 30psi at the rears. I have 18" M1tchy has 20" and K3ith has 21's. I also have 2wd, maybe less weight means less pressure.

[Jim Walker]

After reading this post decided to check the pressure in our Q7 & was surprised to find that the offside rear was 20 PSI out. So as a test I let 8 PSI out of the front tyre & the TMPS came up & alerted me of this.
Do you think the rear sensor could be faulty? Or is this just over the past 10 months since we got the car?

[M1tchy]

That's random and not good. Now they are at the correct pressures have you told the MMI they are right?

[Jim Walker]

Yes told the system they are at the correct pressure then let pressure out of all the tyres 1 at a time & all seems to be working fine. Going to keep a check on it over the next few weeks.

[Furillo]

These are a nice finishing touch.

http://http://www.amazon.co.uk/Black-Audi-Metal-Chrome-Valve/dp/B00A9K0KEW (http://http://www.amazon.co.uk/Black-Audi-Metal-Chrome-Valve/dp/B00A9K0KEW)

[soft]

If you use nitrogen instead, it will hold the pressure better, and you need green caps!

[Jim Walker]

Soft who will fill with nitrogen & where do i get the correct caps from?

[soft]

Soft who will fill with nitrogen & where do i get the correct caps from?
I don't know in your area, I'm in Norway:/)
Here most well equipped tire stores offer this, the caps included.
i belive the pressure stay correct for more than 3 times the duration, compared with air.
the nitrogen will also keep the tyre dry inside, meter for the rubber.
price in Norway is around 10 pounds a wheel.

[M1tchy]

Soft who will fill with nitrogen & where do i get the correct caps from?

Pretty much anywhere does them. I got mine done at kwikfit for free on my last car


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[Phutters]

Soft who will fill with nitrogen & where do i get the correct caps from?Since it's absolutely none of my business I wouldn't even contemplate suggesting how you spend your money, but it might be worth bearing in mind that good old Aberdonian air is already 78% nitrogen.

Here's a bit of what's gone before... (http://www.vwaudiforum.co.uk/forum/showthread.php?142353-Nitrogen-in-tyres)

[soft]

Since it's absolutely none of my business I wouldn't even contemplate suggesting how you spend your money, but it might be worth bearing in mind that good old Aberdonian air is already 78% nitrogen.

Here's a bit of what's gone before... (http://www.vwaudiforum.co.uk/forum/showthread.php?142353-Nitrogen-in-tyres)

If you go Helium the tyre noise might go down?, and the car would "fly" through the curves :-)

[MarkTM]

I was sceptical about nitrogen tyre filling, however my (albeit limited) use showed:

1) Little or no loss over months compared to air
2) Little or no temperature/pressure increases after long drives*

Yep even a nitrogen filled tyre will only be circa 95% nitrogen

*The gases should heat up the same way but I think it has too do with the fact there is more moisture in an air filled tyre? That said only a few PSI difference according to my aftermarket TPMS

I don't bother any more as simply don't do the miles and simply check weekly

[Phutters]

Yep even a nitrogen filled tyre will only be circa 95% nitrogenQuite.

And it doesn't take into account the massive faff of having to get them topped up somewhere that has the facilities rather than just digging your dad's old footpump out of the boot.

[MarkTM]

You can actually buy a bottle of nitrogen and do it yourself :)

I simply found that the incidence level of having to dig out the footpump was reduced 3 fold+

Why your dad's, surely if you can afford an A7 you can push the boat out and get yourself one? Go on you know it makes sense! :D

[Phutters]

Why your dad's, surely if you can afford an A7 you can push the boat out and get yourself one? Go on you know it makes sense! :DPshaw. I can't afford an A7.

I didn't realise you had to actually own an A7 to post in the A7 section ;)

[MarkTM]

Me neither (humble A6 here), but was looking at an A7 demonstrator last week. But having seen specs on the new one will hold off and get one with the matrix LED lights :)

[Phutters]

Me neither (humble A6 here), but was looking at an A7 demonstrator last week. I've been thrown off the premises for pressing my greasy hooter up against the showroom windows so often I've given up dreaming what it'd be like to be rich.

'Look, it's that tramp again. Someone call security...'