Do I need this much pressure?

W

wbwanzer

Joined
Mar 28, 2007
Messages
387
Location
York, Pa.
My recently purchased 2019 Audi S3 is speced on the door placard for 41 psi. The tires are 225/40ZR18 Continental DSW 06. 41 psi seems an awful lot of pressure to me. I've been driving a long time and don't remember ever having a tire need that much pressure. The Audi S3 (think A3) is a small car weighing about 3500 pounds. My Kia Sorento which is much larger and weighs about 4100 pounds only calls for 34 pounds.

So I realize that the S3 is a sporty car. Is that why it calls for 41 so that corners can be 'carved' at higher speeds? I'm not racing, tracking or auto crossing the car. I push it in corners now and then but I mainly wanted this car for the fun acceleration. If it takes me a tenth of a second longer to come out of a corner, it's no big deal. So can I run 35 pounds without problem? I always thought that under inflating would cause the inner and outer edges to wear. And over inflating will cause the center tread to wear. The ride from the rear suspension is a little harsh anyway, so 35 would help with that. So do you folks see any reason why I couldn't run 35 pounds in all tires even though the placard calls for 41?

As always, thanks for your knowledgeable input.
 
What is the load rating on those tyres in that size? You need more pressure because of the tiny sidewalls. The Kia will have much taller sidewall and higher load rating on the tyres. You run the risk of destroying tyres and wheels with lower pressures on bad road surfaces as well as overheating the tread and belts on good surfaces. So there's no guarantee 35 psi will go well, nor that it won't go well.
 
If you can feel a difference between 41 psi and 35 psi on a tire with ~3.5" of sidewall you have a much more sensitive ride-o-meter than I do.

I had DWS on my WRX back in ~2012 and they had some of the softest sidewalls, even compared to regular old touring all seasons and were pretty lazy to steering inputs so if there's an "ultra high performance" all season that might ride at all better at lower pressure, it's those. Mine needed 45+ psi to not scrub on the sidewalls in even mildly spirited driving. I kind of hated them, honestly. They're barely a performance tire.
 
wbwanzer said:
My recently purchased 2019 Audi S3 is speced on the door placard for 41 psi. The tires are 225/40ZR18 Continental DSW 06. 41 psi seems an awful lot of pressure to me. I've been driving a long time and don't remember ever having a tire need that much pressure. The Audi S3 (think A3) is a small car weighing about 3500 pounds. My Kia Sorento which is much larger and weighs about 4100 pounds only calls for 34 pounds.

So I realize that the S3 is a sporty car. Is that why it calls for 41 so that corners can be 'carved' at higher speeds? I'm not racing, tracking or auto crossing the car. I push it in corners now and then but I mainly wanted this car for the fun acceleration. If it takes me a tenth of a second longer to come out of a corner, it's no big deal. So can I run 35 pounds without problem? I always thought that under inflating would cause the inner and outer edges to wear. And over inflating will cause the center tread to wear. The ride from the rear suspension is a little harsh anyway, so 35 would help with that. So do you folks see any reason why I couldn't run 35 pounds in all tires even though the placard calls for 41?

As always, thanks for your knowledgeable input.
Click to expand...
First off congrats on your new car. The Audi is a great car👍
I drive a 2020 GTI and like the Audi run a similar tire pressure (39 psi on 225/40/18). I Believe VW/Audi do this for 2 good reasons.
1. Better fuel economy.
2. To protect the rims.

These cars with low aspect ratio side walls have a tendency to bend rims. If you drop the tire pressure your likely to have more sidewall flex resulting in a higher chance of bending a rim.

So stick to the recommendation by the manufacturer for the tire size on your vehicle. VW's engineers know better than we do👍😁

Enjoy your car😁
 
Yup, you need that pressure.

A 225/40R18 is a pretty small tire. It's the equivalent to a 175/70R13.

Plus there are other reasons.

That is such a low aspect ratio you need the pressure to keep from pinching the sidewalls if you hit a pot hole.

You also need the pressure for the handling.

And the fuel economy, and the wet traction.
 
JRed said:
If you can feel a difference between 41 psi and 35 psi on a tire with ~3.5" of sidewall you have a much more sensitive ride-o-meter than I do.

I had DWS on my WRX back in ~2012 and they had some of the softest sidewalls, even compared to regular old touring all seasons and were pretty lazy to steering inputs so if there's an "ultra high performance" all season that might ride at all better at lower pressure, it's those. Mine needed 45+ psi to not scrub on the sidewalls in even mildly spirited driving. I kind of hated them, honestly. They're barely a performance tire.
Click to expand...
I agree, I was a DWS 06 guy for a couple sets on my Honda Fit, but when I them put on my lowered Kona AWD they were horrible. I flat spotted every morning. I had to have 45 PSI and the side walls still rolled over. They were just for my winter tires, and I still hated them. I swapped them out on warranty and bought a set of Continental Sport A/S that are only avalible at Discount Tire that had the UHP summer sidewall in it. a far better and stiffer tire then the DWS 06, and had an aggressive tread pattern for using it as a winter tire.

I run all my tires between 37 to 40 cold anyways since I sport drive daily. I even get surprisingly even wear this way too with -1.5 camber on all 4s. I am running Michelin Pilot Sport A/S 3+ now and I run them at 38 to 40 cold, depending on weather and time of year. I use these as my summer tire becase I can afford to replace 200/300 wear ( Michelin PS 4S) rated tires every summer.

A co-worker sold his Golf R and now has a Audi S3 and he was a 35 psi guy since he doesn't sport drive as much. He upped his PSI to 40 on his Audi S3 and is keeping it there. He has Goodyear Eagle F1 Asymmetric All-Season which would be superior to DWS 06 since he said it has a nice stiff sidewall. But then again if you drive your car easy the DWS 06 would be a softer more comfortable tire.
 
Last edited:
Mainia said:
I flat spotted every morning. I had to have 45 PSI and the side walls still rolled over.
Click to expand...
Man I forgot about the flat spotting but it was BAD. The WRX wasn't my daily driver and it would sit for a week or more at a time in the winter. First time I drove on them after it sat for a while I was SURE something was broken.

I remember when they were delivered I went to pick one up by the sidewall and it was so thin and squishy I was like "These are going to suck bad..." Sometimes you hate being right 😅
 
Check your owners manual. Audi products only list the pressure for maximum load on the door jamb. For normal load, the pressures are only found in the owners manual.
 
My BMW X1 @ 3700# recommends that high 41 psi for over 100 mph. I think they assume you'll check that one hot so it's not to high.

The stock 225/45r18 Pirelli P7 run flats would lose front traction at anything nearing 41 on the track.

However, I put the lower 225/40r18 Michelin PS4S up front, and 255/35r18 rears. I found the wear and cornering are close to best at 32 front cold and 35 rear cold. that becomes maybe 35 and 38 during normal driving.

Also, with a soft Hankook ventus v12 in 225/40r18 on my RX8, it seemed I needed 46 front 43 rear for a year until they hardened, and then, 35 psi.
 
I've never seen hot pressures in any jamb or maintenance booklet/owners manual. But cold pressures do go up with load, speed and depend on the tyre size and/or engine.
 
There's always a maximum pressure marked on the tire itself. Running close to that will have the best mpg, though handling may suffer.
 
OK guys. I come to you hat in hand, to say that I have screwed up. I had seen in the owners manual a few weeks ago, apparently at a quick glance, that the manual says "The correct tire pressure for tires mounted at the factory is indicated on the label". The label being the door placard. If I had read further I would have seen "Use the tire pressure specified for a normal vehicle load when the vehicle is partially loaded > table on page 351". Looking at that table now, I see for my S3 sedan with 225/40 R18 92Y normal load (2/3 people) front pressure of 38 and rear of 35. So I can lower the pressure a little.

Again, thanks to all who posted. I feel a bit like a moron for coming here to ask about the pressure when it was given to me in the manual, if I had just looked a little further.

Oh well. It's not my first and probably won't be my last goof up.
 
wbwanzer said:
OK guys. I come to you hat in hand, to say that I have screwed up. I had seen in the owners manual a few weeks ago, apparently at a quick glance, that the manual says "The correct tire pressure for tires mounted at the factory is indicated on the label". The label being the door placard. If I had read further I would have seen "Use the tire pressure specified for a normal vehicle load when the vehicle is partially loaded > table on page 351". Looking at that table now, I see for my S3 sedan with 225/40 R18 92Y normal load (2/3 people) front pressure of 38 and rear of 35. So I can lower the pressure a little.

Again, thanks to all who posted. I feel a bit like a moron for coming here to ask about the pressure when it was given to me in the manual, if I had just looked a little further.

Oh well. It's not my first and probably won't be my last goof up.
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No worries at all. It is something that is somewhat peculiar to Audi. Most brands only have one specified pressure.
 

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Check the gas cap door too. My Mercedes also has two sets of tire pressures listed on the gas cap door which is different than the door placard. I think the higher pressure is for full load or high speed driving.
 
Jetronic said:
What is the load rating on those tyres in that size? You need more pressure because of the tiny sidewalls. The Kia will have much taller sidewall and higher load rating on the tyres. You run the risk of destroying tyres and wheels with lower pressures on bad road surfaces as well as overheating the tread and belts on good surfaces. So there's no guarantee 35 psi will go well, nor that it won't go well.
Click to expand...

This is exactly right.

Look in the owners manual, it will usually have pressures for a vehicle with no cargo and 1-2 people and pressures for a full load. The pressure on the door jamb is only the full load specs.

For example my car is 45 front , 41 rear on the sticker but in the manual it's 39f, 35r for regular load.

Edit - sorry should have read the whole thread
 
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