DRC and tyre pressures - am I wrong?

[stu]

Since I got my RS4 I've always used 38/35psi as per the label in the door. The car doesn't seem to handle as well even a few PSI above or below that, although it might just be my imagination.

I've often wondered if the DRC, with it's diagonally linked dampers, somehow magnifies the effects of under/overinflated tyres.

Is there any milage in that theory? I'd love to know.

[S4WON]

Ive just bought a "new to me" B7 RS4 and am also curious about tyre pressures. as the OP says, the offical pressures are 38/35 yet from my touring of the internet, it seems everyone has a different idea of what is correct.

Any info from the B7 pros on tyre pressures for 255 35 19s much appreciated, if it makes any difference im running Michellin Super Sports.

thanks

[KikapuRS]

I run 35 all round on my Goodyear Eagle F1 Assy 2s

[sonny]

I run 35 all round on my Goodyear Eagle F1 Assy 2s

To low imo, to low for the fronts due to engine, bet those babies heat up quickly.

[Graze]

My tyre guy recommended 40/38 in my 275/30/19's using nitrogen

Been very happy with that

And as thy don't heat up like air probably similar to 38/35 pressures

Graze

[KikapuRS]

I run 35 all round on my Goodyear Eagle F1 Assy 2s

To low imo, to low for the fronts due to engine, bet those babies heat up

I run 35 all round on my Goodyear Eagle F1 Assy 2s

To low imo, to low for the fronts due to engine, bet those babies heat up quickly.

I see your point Sonny, my logic was that the contact patch would be greater, especially under braking, therefore improving front end grip. Interestingly enough the fronts aren't wearing at an excessive rate, maybe I need to push harder! !

[sonny]

I run 35 all round on my Goodyear Eagle F1 Assy 2s

To low imo, to low for the fronts due to engine, bet those babies heat up

To low imo, to low for the fronts due to engine, bet those babies heat up quickly.

I see your point Sonny, my logic was that the contact patch would be greater, especially under braking, therefore improving front end grip. Interestingly enough the fronts aren't wearing at an excessive rate, maybe I need to push harder! !

You will compromise on handling and fuel economy. On track i dropped to 40psi hot from standard pressures. This puts them at 33 cold, however i would never go out on track with them tat low im not made of money lol

[adsgreen]

My tyre guy recommended 40/38 in my 275/30/19's using nitrogen

Been very happy with that

And as thy don't heat up like air probably similar to 38/35 pressures

Graze

Sorry to break it to you but nitrogen expands the same as any other gas.The effect is called Charles law and is well known in thermodynamics (co2 filled tyres, n2 filled or even dehumidifier air all expand the same amount).
The issue is with water moisture which only comes into play when you approach 100c and it turns to steam. If you have road tyres hitting 100c internal temp on the road then you have other issues.
Tried nitrogen and even on track I found it more a pita than anything else.

[PetrolDave]

My tyre guy recommended 40/38 in my 275/30/19's using nitrogen

And as thy don't heat up like air

As adsgreen has said ALL gasses expand to the same extent, nitrogen "expanding less than air" is another great 21st Century urban myth.

[S4WON]

ok guys...

so do I shoot for 38F and 35R then?

[PetrolDave]

When I had 275/30 19" Goodyears I was advised to increase the pressures by 0.1 bar to 2.7 front and 2.5 rear - that's 39F and 36R (and adjust the thresholds on the TPMS accordingly).

[RIV]

[quote]When I had 275/30 19" Goodyears I was advised to increase the pressures by 0.1 bar to 2.7 front and 2.5 rear - that's 39F and 36R (and adjust the thresholds on the TPMS accordingly).
[/quote

Going off topic, did you find when running 275's you suffered with tyre wear on the front inner edge? I've always had 275's ever since I bought my car but have found they scrub quickly, I also get my alignment checked twice a year

[Surrey Sam]

Silas, I'm wondering if the wider tyres have introduced a tiny bit more negative camber? Your alignment people I presume are keeping to the factory numbers which is optimised for the 255 section tyres, hence a little more wear on the inside edge. Just a guess here

[S4WON]

ok', so turns out previous pressure was 35F and 33R. ive pumped up to 38/35 and am very happy with the results, certainly feels less skittish when pushing on.... for interest at the end of the run, the temps were approx 4 psi higher all round.

[RIV]

Silas, I'm wondering if the wider tyres have introduced a tiny bit more negative camber? Your alignment people I presume are keeping to the factory numbers which is optimised for the 255 section tyres, hence a little more wear on the inside edge. Just a guess here

You could well be correct Sam, I'm thinking about changing back to the standard size tyres