What Pressure Should I Run?

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Originally Posted By: gaijinnv
Originally Posted By: geeman789

So why is VW spec'ing these unusually high rear pressures...?



To control understeer - it's not always just about load limits
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It's gonna take way more than pumped up rear tires to minimize understeer on the typical FWD ...

This thread seems to have revealed that the air pressure placard may not always be the best psi for most drivers...

Funny seeing a Mazda 3 , a similar sized FWD car, spec'ing 32 / 32 ...

Or my Impreza, with the same sized tires, but more weight on the rear due to AWD, spec'ing 33 f / 32 r...

The tires have adequate load capacity at any reasonable psi above 30... some experimentation may be in order...
 
Unless it is a misprint I would go with the recommendation. You could verify with your dealer, I guess.

Is this a convertible by any chance? They might be a little heavier in the rear. I had an Accord wagon and it was heavy in the rear and the manual commented that it should have more PSI in the rear because of that, and additional if fully loaded with cargo.
 
Originally Posted By: datech
Unless it is a misprint I would go with the recommendation. You could verify with your dealer, I guess.

Is this a convertible by any chance? They might be a little heavier in the rear. I had an Accord wagon and it was heavy in the rear and the manual commented that it should have more PSI in the rear because of that, and additional if fully loaded with cargo.
Nope it's a coupe.

Lowered it down to 35 front/ 38 rear, somewhat better. I think I'll keep this psi.
 
Originally Posted By: datech
Unless it is a misprint I would go with the recommendation. You could verify with your dealer, I guess.

Is this a convertible by any chance? They might be a little heavier in the rear. I had an Accord wagon and it was heavy in the rear and the manual commented that it should have more PSI in the rear because of that, and additional if fully loaded with cargo.


It is a USA mandated misprint... a result of the general driving populations inability to THINK.

This VW Beetle is similar in layout , weight and weight distribution to most FWD cars... most of which spec a much much lower tire psi, with more in the fronts ( where that lump of engine/tranny sit...) or equal front /rear psi...

Why would you just blindly follow the factory recommendation...? Are VWs somehow exempt from basic principles of physics...?

More weight , more load, higher psi. Higher speed, greater centrifugal forces, stress and heat, higher psi..

But for a lightly loaded, average driven FWD car, the "factory..." settings are overkill. I would try something much lower, the tires have more than adequate load capacity at even 32 f / 28 rear...

If you think it rides stiff, those pressures are why. But if you like the way it handles, and feels, thats fine too...!
 
What's actually surprising is regardless of what tires it has on it, and at 40 psi all the way around the car handles fantastically. It can REALLY take a corner, basically no body roll at all. Other cars I've driven when you take a corner really fast it squeals the tires and understeers, this thing is just point & go! I might lower them a little more, the rear doesn't feel to stiff, even with it pumped up more than the front. Any cracks and bumps in the road I only feel in the front.
 
I think if you look in the owners manual you will find a tire pressure for normal load. My 2000 Jetta (same chassis as Beetle) says on the sticker on the gas door 26 front and rear (I run 28) for normal load and 30 front and 41 rear for maximum load. My 2007 Audi A4 only lists full load on the door sticker and gives a lower pressure for normal load in the owners manual.
 
Originally Posted By: silveravant
I think if you look in the owners manual you will find a tire pressure for normal load. My 2000 Jetta (same chassis as Beetle) says on the sticker on the gas door 26 front and rear (I run 28) for normal load and 30 front and 41 rear for maximum load. My 2007 Audi A4 only lists full load on the door sticker and gives a lower pressure for normal load in the owners manual.


The Porsche in the article I linked to does the same. The placard says 36 f / 44 r , but the owners manual lists 3 or 4 other options, with the light load comfort setting ( yes, Porsche has a comfort setting...) being way down at 31f / 34r. They do caution that the recommended max speed drops down to only 165 mph though... but also state the car handles better at the lower pressure.

http://www.edmunds.com/porsche/911/2013/...e-pressure.html
 
I must be the only one who gets increased center tread wear if I go above 1-2 PSI over door placard.
 
Originally Posted By: badtlc
I must be the only one who gets increased center tread wear if I go above 1-2 PSI over door placard.
I almost always overinflate tires a bit and have never had them wear more in the center. My previous set of tires were usually set around 40 psi for the 62,000 miles they were on the car and the edges wore much more than the center
 
Originally Posted By: silveravant
I think if you look in the owners manual you will find a tire pressure for normal load. My 2000 Jetta (same chassis as Beetle) says on the sticker on the gas door 26 front and rear (I run 28) for normal load and 30 front and 41 rear for maximum load. My 2007 Audi A4 only lists full load on the door sticker and gives a lower pressure for normal load in the owners manual.
Odd, I just checked my owners manual and it says to look on the door placard
2duigw6.jpg
 
I must bumped from 32 to 40 in the rear of my Jetta (34 or 36 in front), and it's vastly better. At 32 the rear of the car wanted to come around on any steering input. Now it is planted as it ever was.
 
Originally Posted By: Nick1994
Originally Posted By: badtlc
I must be the only one who gets increased center tread wear if I go above 1-2 PSI over door placard.
I almost always overinflate tires a bit and have never had them wear more in the center. My previous set of tires were usually set around 40 psi for the 62,000 miles they were on the car and the edges wore much more than the center


On my Honda van, the summer all-seasons (Michelin Defender...) like a higher pressure up front, I run 38 + psi , or they wear the edges of the tire...

The winter tires (Nokian Hakka R...) however, are the opposite, they wear in the center if pressure is above about 35 psi.

On my Subaru , I've noticed no difference in wear from 30 psi up to 40 psi... only changes in ride and handling...

My usual experience is that WIDE tires always wear the middle faster, and narrow tires are less sensitive.

And my van is known to wear the outside edge of tires... a heavy vehicle that leans hard on the fronts...

As I said before, some experimentation may be needed to find "your..." and your cars, ideal pressure.
 
I know this sounds crazy but when I upsized the Kitacamry from 15 to 17s and from OEM rubber to UHP tread, I upped the PSI from 29 (doorjamb recommendation) to 44 (max for the tire is 51psi) and after 15k and 2 rotations, the wear is even from shoulder to shoulder on all 4.
 
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Originally Posted By: KitaCam
I know this sounds crazy but when I upsized the Kitacamry from 15 to 17s and from OEM rubber to UHP tread, I upped the PSI from 29 (doorjamb recommendation) to 44 (max for the tire is 51psi) and after 15k and 2 rotations, the wear is even from shoulder to shoulder on all 4.
44 psi on bigger wheels, must be pretty stiff, but it is a Camry. They ride pretty soft. It's strange but I actually kind of liked how my 97' handled and rode, it had all new suspension and stuck corners pretty good. I did 80 mph around most curves on my road trip to Montana.
 
I just checked the 2013 VW Beetle TDI and the owners manual says to check the door placard too. It's a bigger and heavier car but calls for 31 psi front and rear, although it does have bigger tires.

2rqjdps.jpg
 
FYI:

Tire wear is not very sensitive to inflation pressure. There are other things that have more of an effect, such as alignment and driving style.

Also, it isn't a given that tires will wear unevenly if they are not properly inflated (as in not inflated per the placard or not per the load table). Ergo, it is quite possible to get uneven wear even if the tires are properly inflated. Also, it is quite possible to get even wear, in spite of improper inflation pressure.
 
Originally Posted By: Nick1994
I just checked the 2013 VW Beetle TDI and the owners manual says to check the door placard too. It's a bigger and heavier car but calls for 31 psi front and rear, although it does have bigger tires.

2rqjdps.jpg



Door sticker says to check owners manual for additional information. If all the owners manual says is to check sticker that's pretty crazy. Could get pretty tiring going from one to the other without knowing when to stop.
 
Originally Posted By: Nick1994
Originally Posted By: KitaCam
I know this sounds crazy but when I upsized the Kitacamry from 15 to 17s and from OEM rubber to UHP tread, I upped the PSI from 29 (doorjamb recommendation) to 44 (max for the tire is 51psi) and after 15k and 2 rotations, the wear is even from shoulder to shoulder on all 4.
44 psi on bigger wheels, must be pretty stiff, but it is a Camry. They ride pretty soft. It's strange but I actually kind of liked how my 97' handled and rode, it had all new suspension and stuck corners pretty good. I did 80 mph around most curves on my road trip to Montana.


The 02-06 Camry base/LE is reportedly the softest of all camry rides...upsizing/upping the PSI has made the ride very responsive, firm but not stiff/jarring...

I loved having my BMW 2002 in Montana and driving through switchbacks of the Rockies...
 
Originally Posted By: CapriRacer
FYI:

Tire wear is not very sensitive to inflation pressure. There are other things that have more of an effect, such as alignment and driving style.

Also, it isn't a given that tires will wear unevenly if they are not properly inflated (as in not inflated per the placard or not per the load table). Ergo, it is quite possible to get uneven wear even if the tires are properly inflated. Also, it is quite possible to get even wear, in spite of improper inflation pressure.


What you are stating is contrary to virtually every published word on tire wear... !

Do you mean within a reasonable range of inflation pressures...?

Grossly under-inflated tires ride on the edges, as supported by heat measurements and glass plate high speed photography...

How can they not wear more than a "properly.." inflated tire...?

Over-inflation seems like it would be less of an issue... but it still seems to be on certain cars / tires...
 
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