What Pressure Should I Run?

[Nick1994]

Just got a new set of Pirelli Citurato P7's on my car last week, replaced the awful Michelin HydroEdge's. It has completely changed the car, no more crooked steering wheel and pulling to the right and is smooth and quiet on the freeway. They're actually very noticeably softer on rough roads and on speed bumps (really!)

So what pressure should I run? I typically overinflate tires just a little bit. What I want is long treadlife and perhaps a little extra mpg. I'm not too worried about extreme comfort, it certainly doesn't have Cadillac suspension

The door placard recommends front at 34 PSI and rear at 39 PSI.

What do you guys think? Bump it up a couple pounds up front? I always pumped the old tires to close to 40 psi and refilled every couple months. They went 62k miles and still had an averge of 7/32" of tread.

Thanks.

 

[Quattro Pete]

A couple of PSI above door placard should be fine, as long as you don't exceed the max PSI noted on the sidewall.

 

[HTSS_TR]

I usually add about 3-4 PSI to the front to have faster steering, also add 1-2 PSI to the rear to have firmer ride.

 

[HerrStig]

A couple over is OK. Your roads are no doubt in better shape than those of the frozen north, so beating the suspension up is less of a problem. Just keep in mind the sidewall "max" pressure isn't that number you shoul dbe using.

 

[splinter]

Originally Posted By: Nick1994
...I always pumped the old tires to close to 40 psi and refilled every couple months. They went 62k miles and still had an averge of 7/32" of tread.

Thanks.


Sounds like you’ve found a good recipe.

I get a kick out of the “for continuous operation in excess of 100-mph increase recommended pressures by 4-psi” admonition on our M-B’s fuel filler door.

Operator’s manual states “higher tire pressures to account for higher speeds and/or loads are perfectly permissible with light loads although the ride may be somewhat harder.”

 

[mrsilv04]

Why not start at the manufacturer's recommendation, run those pressures for a while as a 'baseline'... and then go from there?

 

[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

 

[geeman789]

Originally Posted By: Nick1994
Just got a new set of Pirelli Citurato P7's on my car ...

....The door placard recommends front at 34 PSI and rear at 39


Seems like a strange pressure spec... is it for the Beetle...?

Small, front wheel drive car, weight distribution usually in excess of 60 % on the fronts... almost every similar car specs more psi on the fronts, and typically much lower psi all round.

My pudgy Impreza only specs 33 f / 32 r...

Not sure why the rear spec psi is so high...?

I would try lower, like 32f / 30r... and experiment from there... what size are the tires...?

 

[datech]

WEll, for that 'sandy beach' ride I 'd go with half, maybe 15 pounds.

Then again, maybe not.

What I sometimes wonder is how to gauge the right pressure when the temperature swings between day and night are kind of extreme, like in Arizona when it might be in the 60's day, but 30's t night.

I always err on the high side. I would rather have too much than blow a tire because it's too low.

 

[Nick1994]

Originally Posted By: geeman789
Originally Posted By: Nick1994
Just got a new set of Pirelli Citurato P7's on my car ...

....The door placard recommends front at 34 PSI and rear at 39


Seems like a strange pressure spec... is it for the Beetle...?

Small, front wheel drive car, weight distribution usually in excess of 60 % on the fronts... almost every similar car specs more psi on the fronts, and typically much lower psi all round.

My pudgy Impreza only specs 33 f / 32 r...

Not sure why the rear spec psi is so high...?

I would try lower, like 32f / 30r... and experiment from there... what size are the tires...?


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

 

[The Critic]

Originally Posted By: Nick1994
Originally Posted By: geeman789
Originally Posted By: Nick1994
Just got a new set of Pirelli Citurato P7's on my car ...

....The door placard recommends front at 34 PSI and rear at 39


Seems like a strange pressure spec... is it for the Beetle...?

Small, front wheel drive car, weight distribution usually in excess of 60 % on the fronts... almost every similar car specs more psi on the fronts, and typically much lower psi all round.

My pudgy Impreza only specs 33 f / 32 r...

Not sure why the rear spec psi is so high...?

I would try lower, like 32f / 30r... and experiment from there... what size are the tires...?


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


I've seen quite a few Euro cars that use this approach.

If you want to experiment, I would start with 3psi over the factory spec.

Did you get the P7 or the new P7 Plus? I am deciding between the P7 Plus and the Premier A/S for my next set of tires.

 

[Nick1994]

Originally Posted By: The Critic
Originally Posted By: Nick1994
Originally Posted By: geeman789
Originally Posted By: Nick1994
Just got a new set of Pirelli Citurato P7's on my car ...

....The door placard recommends front at 34 PSI and rear at 39


Seems like a strange pressure spec... is it for the Beetle...?

Small, front wheel drive car, weight distribution usually in excess of 60 % on the fronts... almost every similar car specs more psi on the fronts, and typically much lower psi all round.

My pudgy Impreza only specs 33 f / 32 r...

Not sure why the rear spec psi is so high...?

I would try lower, like 32f / 30r... and experiment from there... what size are the tires...?


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


I've seen quite a few Euro cars that use this approach.

If you want to experiment, I would start with 3psi over the factory spec.

Did you get the P7 or the new P7 Plus? I am deciding between the P7 Plus and the Premier A/S for my next set of tires.
I got the P7 Plus. It's completely changed the car, but the Michelin's were looking pretty sad and were not in good shape at all. Being a diesel and needing a motor mount soon, it's got some vibrations and road noise, mostly just the nature of the beast but by far are much more quiet than my old tires. The only thing I can think of to describe how smooth they are over bumps is its as if the old tires were solid plastic and had no need of air, speed bumps and cracks in the road you could feel every bit of them. With these Pirelli's, I can feel they have a little "give" to them over bumps (in a good way) and it dampens a lot. The old Michelin's (one was cupped badly) and around a sharp curve on the highway at 70 mph was setting off the stability control and braking automatically. These new tires I did 80 mph just for the heck of it and they stuck well. No stability control kicking in.

 

[The Critic]

Originally Posted By: Nick1994
I got the P7 Plus. It's completely changed the car, but the Michelin's were looking pretty sad and were not in good shape at all. Being a diesel and needing a motor mount soon, it's got some vibrations and road noise, mostly just the nature of the beast but by far are much more quiet than my old tires. The only thing I can think of to describe how smooth they are over bumps is its as if the old tires were solid plastic and had no need of air, speed bumps and cracks in the road you could feel every bit of them. With these Pirelli's, I can feel they have a little "give" to them over bumps (in a good way) and it dampens a lot. The old Michelin's (one was cupped badly) and around a sharp curve on the highway at 70 mph was setting off the stability control and braking automatically. These new tires I did 80 mph just for the heck of it and they stuck well. No stability control kicking in.


That's great to hear. Pirelli seems to be getting a lot of new customers with their new "Plus" line of tires (P7 Plus, Scorpion Verde Plus and P4 Plus). TireRack has been slamming them a bit for their wet traction, but I guess this is all relative to your past experiences and your local conditions.

For instance, I recently put a set of Scorpion Verde Plus tires on a 2009 FX35. The previous tires were a well-worn set of Latitude Tour HPs. The Pirellis are excellent in the dry, better riding, ridiculously quiet and decent in the wet. But I wouldn't say that they were drastically better in the wet than the worn out set of Latitude Tour HPs...go figure.

 

[Nick1994]

And you have to admit, they're a darn good looking tire too

 

[CapriRacer]

Originally Posted By: datech
.......What I sometimes wonder is how to gauge the right pressure when the temperature swings between day and night are kind of extreme, like in Arizona when it might be in the 60's day, but 30's t night.......


First, tire wear is not that sensitive to inflation pressure. There are other things that more likely to cause wear issues.

Second, that would only be a 3 psi swing. I'd be more concerned about the difference between 30°F and 100°F.

Originally Posted By: datech
.......I always err on the high side. I would rather have too much than blow a tire because it's too low.


Always a good tactic.

 

[SHOZ]

Too high in the rear will wear the tire in the center, too low in the front will wear the tire on the edges.

 

[supton]

I always liked 40 in my Jetta, at least on the Conti tires. Snow tires did not like that pressure! I think I have 32 right now in the RT43's and it is certainly scary handling, albeit a bit smoother ride.

I ought to put at 40 for today's drive.

 

[Benzadmiral]

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

My gosh. If I went 4-5 psi over the standard 33 on the Regal in this poorly paved state, my teeth would rattle. I do 34 all around unless I know I'll be running for an hour or more on the Interstate. Then I'll do 35 (or 36, if I'll be going to MS or TX, which have smoother roads).

 

[SwampSurvivor]

Originally Posted By: SHOZ
Too high in the rear will wear the tire in the center, too low in the front will wear the tire on the edges.


Some people would disagree, but unless I run my Winterforce tires *AT* 44 or 45 PSI, they will wear the outside edges of the fronts. Only way I can get even wear on them is to run them at the max, on the front. Of course, when it's snowing, I have to drop them to 32 all around

Now that I have the rear alignment sorted out, it doesn't seem to be wearing the rears at all with 32 PSI

 

[Nick1994]

The Beetle is designed to have a little bit of negative camber in the rear and the old tires wore a tiny bit more on the inner edges due to this. Would a higher psi or lower psi help with even tire wear? My way of thinking is if they're real full in the rear then they'll ride more on that inner edge. Not sure though.