If it's wearing because of camber/toe, the only way to fix that is to correct the camber/toe.
What Pressure Should I Run?
- Thread starter Nick1994
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Nick1994
$100 site donor 2024
Originally Posted By: Miller88
If it's wearing because of camber/toe, the only way to fix that is to correct the camber/toe.
The dealership did an alignment 3 months ago so it's in-spec but the design is to have a little negative camber, I assume for cornering.
If it's wearing because of camber/toe, the only way to fix that is to correct the camber/toe.
The dealership did an alignment 3 months ago so it's in-spec but the design is to have a little negative camber, I assume for cornering.
Yup. That and rear toe helps with cornering. What I did to counteract that was to load a few hundred pounds of stuff in the back of my Focus when I got it aligned. That would give them more toe and camber. Then, when nothing was in the back, they would be closer to straight.
Originally Posted By: Nick1994
The car specs 34 psi front and 39 psi rear from the factory, odd I know. They're the stock size at 205/55-16
A typical 205/55/16 xl 94 tire is rated a 1146 lbs at 30 psi, and this moves up to 1268 lbs at 35 psi... not a huge change. At 41 psi , the load capacity is up to 1433 lbs...
Most car makers spec tire psi as a suspension and ride tuning characteristic, not purely as a load capacity spec. Most "reasonably sized for the application..." tires have adequate load capacity over a wide range of psi settings.
The car specs 34 psi front and 39 psi rear from the factory, odd I know. They're the stock size at 205/55-16
A typical 205/55/16 xl 94 tire is rated a 1146 lbs at 30 psi, and this moves up to 1268 lbs at 35 psi... not a huge change. At 41 psi , the load capacity is up to 1433 lbs...
Most car makers spec tire psi as a suspension and ride tuning characteristic, not purely as a load capacity spec. Most "reasonably sized for the application..." tires have adequate load capacity over a wide range of psi settings.
Originally Posted By: hotwheels
Originally Posted By: mrsilv04
Why not start at the manufacturer's recommendation, run those pressures for a while as a 'baseline'... and then go from there?
The car manufacturer's recommendations are usually based on giving comfort precedence over driving dynamics. Many cars will recommend various tire pressures for various loads depending on number of passengers and amount of luggage.
4 to 5 psi over the base recommendation is a good starting point for improved handling and cooler running tires on passenger cars, and for high-speed driving.
hotwheels
I can't imagine the idiot engineers who came up with those recommended pressures. How about we just start with any random number and go from there. Oh yeah, that's what pumping the rear tires up to nearly 45 pounds would be doing.
Originally Posted By: mrsilv04
Why not start at the manufacturer's recommendation, run those pressures for a while as a 'baseline'... and then go from there?
The car manufacturer's recommendations are usually based on giving comfort precedence over driving dynamics. Many cars will recommend various tire pressures for various loads depending on number of passengers and amount of luggage.
4 to 5 psi over the base recommendation is a good starting point for improved handling and cooler running tires on passenger cars, and for high-speed driving.
hotwheels
I can't imagine the idiot engineers who came up with those recommended pressures. How about we just start with any random number and go from there. Oh yeah, that's what pumping the rear tires up to nearly 45 pounds would be doing.
I seem to recall a company doing just that. Their full framed, solid rear axle, leaf sprung rear SUV rode like the full framed, solid rear axle, leaf sprung truck on which it was based. They arbitrarily told their customers to drop tire PSI to 26 - which caused them to have blowouts and tip over.
Nick1994
$100 site donor 2024
I've got them pumped up to 38 front and 40 rear at 50 degrees outside. They were at 32-33 psi from Discount Tire filling them up. We'll see how it goes.
That' surprising that the Discount Tire didn't fill them.
More than once I've found new tires highly overinflated. IIRC one of the techs told me they did that to make sure they seated well on the rim and being newly mounted the extra air would help.
I guess one good way is to check the contact patch with chalk.
More than once I've found new tires highly overinflated. IIRC one of the techs told me they did that to make sure they seated well on the rim and being newly mounted the extra air would help.
I guess one good way is to check the contact patch with chalk.
On my 2013 Mustang GT I find 3 to 4 psi over the door recomondations about right. As a matter of fact I find 3 to 4 above seems to work best for most cars and trucks I drive.
A friends similar year Golf specs 31 f / 29 r... for basically the same car...?
Not sure why VW specs 39 rear psi on this model...
Not sure why VW specs 39 rear psi on this model...
This...
The half load/full load stuff was used through the 2003 model year. Then a change in the FMVSS codes required only one value be posted, and that the location of the placard be moved to a standardized location (doorjamb). VW, along with some other OEMs, requested a waiver and it was denied. VW then was forced to use the former "full load/above 100 mph" value. This was all brought to by your Federal Gov't's reaction to the Ford Exploder/Firestone Tire debacle.....
Euro tire pressure specs for your car are much much lower, around the 31 / 29 range.
The tire placard is for a max load scenario , including 2 passengers AND a fully loaded trunk/hatch, and sustained very high speeds...
Euro spec tire pressure here...
http://www.puretyre.co.uk/volkswagen-tyre-pressures/
The half load/full load stuff was used through the 2003 model year. Then a change in the FMVSS codes required only one value be posted, and that the location of the placard be moved to a standardized location (doorjamb). VW, along with some other OEMs, requested a waiver and it was denied. VW then was forced to use the former "full load/above 100 mph" value. This was all brought to by your Federal Gov't's reaction to the Ford Exploder/Firestone Tire debacle.....
Euro tire pressure specs for your car are much much lower, around the 31 / 29 range.
The tire placard is for a max load scenario , including 2 passengers AND a fully loaded trunk/hatch, and sustained very high speeds...
Euro spec tire pressure here...
http://www.puretyre.co.uk/volkswagen-tyre-pressures/
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Interestingly, my Honda Element does the same, 33psi front, 35psi rear. The SC (lowered, Fwd only version running on 18" wheels) asks for 32psi all around.
Originally Posted By: supton
Just ran out and checked. My 2004 VW Jetta Wagon, with 195/65 15's says 36 front / 45 rear. Max payload of 503kg or 1,109lb.
No small FWD car needs that kind of pressure in the rear tires... typical weight distribution with driver is up around 65% front / 35 rear...
Tires carrying hundreds of pounds LESS load don't need 45 psi , or 39 or whatever VW specs for US cars...
Euro specs are much much lower, and are the more typical 2 or 3 psi more in the fronts...
Just ran out and checked. My 2004 VW Jetta Wagon, with 195/65 15's says 36 front / 45 rear. Max payload of 503kg or 1,109lb.
No small FWD car needs that kind of pressure in the rear tires... typical weight distribution with driver is up around 65% front / 35 rear...
Tires carrying hundreds of pounds LESS load don't need 45 psi , or 39 or whatever VW specs for US cars...
Euro specs are much much lower, and are the more typical 2 or 3 psi more in the fronts...
VW Beetle specs...
Weight 3000 lbs
Weight distribution: 63 f / 37 r
Approx. Front tire load: 945 lbs
Approx. Rear tire load: 555 lbs
You could run the rears at 25 psi , and still have HUNDREDS of pounds of extra load capacity....
An 89 or 90 load capacity tire can carry about 950 lbs at 25 psi...!
So why is VW spec'ing these unusually high rear pressures...?
Weight 3000 lbs
Weight distribution: 63 f / 37 r
Approx. Front tire load: 945 lbs
Approx. Rear tire load: 555 lbs
You could run the rears at 25 psi , and still have HUNDREDS of pounds of extra load capacity....
An 89 or 90 load capacity tire can carry about 950 lbs at 25 psi...!
So why is VW spec'ing these unusually high rear pressures...?
Nick1994
$100 site donor 2024
Yeah it was pretty rough today at 38 front/40 rear. Gonna bump them down a few notches and see how it rides.
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
So why is VW spec'ing these unusually high rear pressures...?
To control understeer - it's not always just about load limits
Originally Posted By: Nick1994
Yeah it was pretty rough today at 38 front/40 rear. Gonna bump them down a few notches and see how it rides.
My daughter's Mazda3 in my signature also has the P7 A/S+ in 205-55-16. These are "H" Speed Rated. Are yours H or V?
With the door jamb setting of F:32/R:32 on this Mazda3, the P7's are bit on the harsh side(though very quiet). Any higher PSI makes road imperfections and bumps worse. Comparing the P7's to the previous tires, which we kept a bit higher PSI in fact.
Yeah it was pretty rough today at 38 front/40 rear. Gonna bump them down a few notches and see how it rides.
My daughter's Mazda3 in my signature also has the P7 A/S+ in 205-55-16. These are "H" Speed Rated. Are yours H or V?
With the door jamb setting of F:32/R:32 on this Mazda3, the P7's are bit on the harsh side(though very quiet). Any higher PSI makes road imperfections and bumps worse. Comparing the P7's to the previous tires, which we kept a bit higher PSI in fact.
Originally Posted By: geeman789
Originally Posted By: supton
Just ran out and checked. My 2004 VW Jetta Wagon, with 195/65 15's says 36 front / 45 rear. Max payload of 503kg or 1,109lb.
No small FWD car needs that kind of pressure in the rear tires... typical weight distribution with driver is up around 65% front / 35 rear...
Tires carrying hundreds of pounds LESS load don't need 45 psi , or 39 or whatever VW specs for US cars...
Euro specs are much much lower, and are the more typical 2 or 3 psi more in the fronts...
I think mine is about 60/40 distribution, and 3,000lb curb, with a GVWR of apparently 4,100---so I suspect my rear tires may see a heavier loading than Nick. With current regs only allowing posting of the pressure for max loading, that would explain my tires.
The car has been feeling weird ever since I put these tires on, with a low 32psi pressure. I just never thought about bumping them up.
Originally Posted By: supton
Just ran out and checked. My 2004 VW Jetta Wagon, with 195/65 15's says 36 front / 45 rear. Max payload of 503kg or 1,109lb.
No small FWD car needs that kind of pressure in the rear tires... typical weight distribution with driver is up around 65% front / 35 rear...
Tires carrying hundreds of pounds LESS load don't need 45 psi , or 39 or whatever VW specs for US cars...
Euro specs are much much lower, and are the more typical 2 or 3 psi more in the fronts...
I think mine is about 60/40 distribution, and 3,000lb curb, with a GVWR of apparently 4,100---so I suspect my rear tires may see a heavier loading than Nick. With current regs only allowing posting of the pressure for max loading, that would explain my tires.
The car has been feeling weird ever since I put these tires on, with a low 32psi pressure. I just never thought about bumping them up.
Nick1994
$100 site donor 2024
Originally Posted By: Char Baby
Originally Posted By: Nick1994
Yeah it was pretty rough today at 38 front/40 rear. Gonna bump them down a few notches and see how it rides.
My daughter's Mazda3 in my signature also has the P7 A/S+ in 205-55-16. These are "H" Speed Rated. Are yours H or V?
With the door jamb setting of F:32/R:32 on this Mazda3, the P7's are bit on the harsh side(though very quiet). Any higher PSI makes road imperfections and bumps worse. Comparing the P7's to the previous tires, which we kept a bit higher PSI in fact.
Yes they are the 91H rated tires. They were silky smooth when Discount had them at 32-33 psi all the way around.
Originally Posted By: Nick1994
Yeah it was pretty rough today at 38 front/40 rear. Gonna bump them down a few notches and see how it rides.
My daughter's Mazda3 in my signature also has the P7 A/S+ in 205-55-16. These are "H" Speed Rated. Are yours H or V?
With the door jamb setting of F:32/R:32 on this Mazda3, the P7's are bit on the harsh side(though very quiet). Any higher PSI makes road imperfections and bumps worse. Comparing the P7's to the previous tires, which we kept a bit higher PSI in fact.
Yes they are the 91H rated tires. They were silky smooth when Discount had them at 32-33 psi all the way around.
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