What's your PSI?

[MustangEcoboobs]

Just a quick question. What's the best PSI on your tires for performance and gas mileage?

I have a 2015 ecoboost manual with PP. I'm running 37 psi from factory and I average 15 mpg city driving only.

My 0-60 best time is 5.9 seconds shifting at 6k rpm. HELP!

What PSI are you running on your tires?

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[ElAviator72]

I run 32 PSI (per the door jamb sticker recommendation), and I get 26-27 MPG (mostly highway driving).

I asked about tracking the car before (in this forum), and the responses I got said that the Pirelli P-Zeroes get squirrelly up around 37 PSI, so I'd probably try a lower pressure if you're looking for max performance

 

[ElAviator72]

Two more things: 1) my dealer seems to think I need my tires aired up around 38 PSI. Every time I get it back from them, I'm overinflated :doh:
And 2) The PP suspension is already rock hard. Overinflated tires on the street makes for a bone-jarring ride!

 

[cal_gecko]

when I got my car brand new from the dealership a few weeks ago, they had the tires overinflated to 38 as well - My assumption on this was that they did it to help gas mileage - to give a new buyer a positive impression of the gas mileage on their new car. I have since aired them down to 32 psi, which is the widely accepted standard 'optimal' tire air pressure for passenger cars. It provides a good balance between reduced rolling resistance (for improved MPG), good traction for acceleration, and good handling for turns. If you want to improve your straight-line performance/launching - go down to about 27psi, but don't forget to put it back up to 32 or so afterwards, otherwise you will notice some irregular tire wear after a while (it takes hundreds/thousands of miles to notice the difference).

 

[MustangEcoboobs]

Thanks for the replies. I will try to deflate to 32psi and see what it does! Is it safe to keep at 32 psi for long duration?

Also do I measure PSI before or after the tires warm up?

 

[ElAviator72]

Thanks for the replies. I will try to deflate to 32psi and see what it does! Is it safe to keep at 32 psi for long duration?

Also do I measure PSI before or after the tires warm up?

Tire PSI is usually a cold setting (i.e. before the car goes anywhere). Your tire pressure will go up and down based on weather conditions, ambient pressure, etc. I try and check mine once a week. Invest in a good digital tire gauge.

32 PSI is the recommended pressure for normal driving. The owner's manual has a special section covering how to inflate the tires for periods of prolonged driving over 100 MPH, so if you're going out on the track or the autobahn, you might want to consult that section of the owner's manual ;)

 

[bbtt]

I dunno if this has been ask before but does the psi need to be change when you switch to bigger rims and tires?

 

[Glenn G]

43 PSI because extended high speed is a daily thing for me. this gets me even temperature along the entire width of the tire on my pyrometer and anywhere from 10-30 degrees reduction in temperature vs ~32 psi. The Tires i use have relatively soft sidewalls though and the ride is still nice even on lowered suspension.

 

[boardkat]

 

[stangs-R-me]

I've read that the auto mfr's over-inflate tires (compared to door jamb) because there can be delays that keep cars longer at the factory and it can take a while to get to dealers ... they just want to be sure a tire does not get low (or flat) before finally reaching it's destination.

Dealers likely do it because cars can sit there a while and they don't want to be constantly trying to maintain door jamb pressure in all their inventory.

And when a dealer's tech does it, I'm guessing it is out of habit as most customers never look at their tires and it just keeps them happier longer if a slow leak were to develop.


I run mine at 36 PSI cold (stock 235/50-18 GoodYear UHP-A/S).

Doug

 

[ElAviator72]

I dunno if this has been ask before but does the psi need to be change when you switch to bigger rims and tires?

You're kind of in no-mans-land on that one. If it isn't a factory tire size, then the factory has no data on proper inflation pressure. I've seen websites that have tools that will recommend proper inflation pressures when you upsize/oversize the tires, and it takes into account the make and model of the base vehicle...that's probably the best advice you'll get on that, other than networking with people running the same tires/tire size on the same car

 

[ElAviator72]

Wow, surprised that tire has a Schrader valve on it! I thought Schrader (i.e. the standard car tire valve) valves were only good up to about 200 PSI or so...

 

[HappySquirrel]

Wow, surprised that tire has a Schrader valve on it! I thought Schrader (i.e. the standard car tire valve) valves were only good up to about 200 PSI or so...

I think whoever wrote that "#500psi" goofed. If you look closely the tire sidewall says 50 psi max. Whoops!

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