What Tire Pressures Are You Running for Street Use?

[Capri to ST]

The factory recommended ones of 39F and 36R, or something different? This would be for a fairly aggressively driven street DD, mostly with just me, I almost never have rear seat passengers or carry big loads. My goal would be to soften the ride a little without a significant decrease in the quickness and responsiveness of the steering. If lowering pressures affects that adversely, I'll just run what the factory suggests, but just wanted see what others were doing.My first reaction when I saw the recommended pressures of 39/36 was "Wow, that's really high." That said, I won't change that without a good reason, because I believe the engineers who designed this car knew what they were doing and clearly put a lot of thought into the details.

I searched and didn't find much on the forum on this topic, just a few discussions in the context of different factory recommendations for the US 4-door vs. the rest of the world's 2-door.

NOTE- That's cold pressures, taken after the car has sat for at least a few hours, more normally overnight.

 

[Thirty-Two]

I run 41F/38R. Better steering, less roll, grip breaks more predictably. Wear hasn't been abnormal.
My recommendation is to keep it factory for DD. Lowering the tire pressure for the car/stock tire combo like this won't help much in terms of providing both comfort and performance. Especially if you're driving aggressively, tire contact and form is essential. If you do 55+ alot, I stress in keeping the factory spec. If you're going anywhere near 80, bump it up to 40F/37R.
If you do chose to lower it, keep the 2psi difference and don't lower more than 2 psi. So 37F/34R at most. Test it out, you'll feel it, it''ll become more apparent with higher speeds and hard cornering, due to the type of car this is.
Also do all this on rested "cold" tires.

 

[Zormecteon]

I'll just throw in the importance of keeping the difference between front and rear as suggested by the factory. The Corvair came with just such a suggestion (but in reverse, 15 front, 26 rear). This is done as a way to balance the grip F/R. In the Corvair, filling to even all around made the car tail happy and "unsafe", at least according to Ralph Nader. My Sprite also suggests a differential and it too is known to be tail happy. That the factory suggests a differential biasing the front (on a front wheel drive car) suggests to me that it will have a greater tendency to "plow" if this differential is NOT maintained. (I have done NO TESTING to back up this thought. I'm sure some of the track guys can weigh in)

 

[Brickell FIST]

I'm a bit of a renegade when it comes to tire pressure. I max mine out and have had no negative side effects. Better gas and tire wear. Probably not the best for drag racing but this car isn't designed to do that. It's not for everyone. I'm just going off of what I was told to do from two different driving courses EVOC and Bobby Ore's stunt school. NOBODY drives cars harder than those two events. Period.

 

[Intuit]

Came from dealer with 44PSI front and rear; pseudo warm. I left it that way.
The rear does start to step out when braking harder at higher speeds while cornering.
Given the suggestion here I might opt to change the front/rear pressure differences to match manufacturer spec. (while keeping higher overall pressures)

The primary reason I've not modified the dealer set pressures is concern with the very rough streets here, damaging the wheels; it's a *much* smaller sidewall than I'm used to. I also want to monitor for pressure change and will check them at some point in the future.

It came with Perelli Summer tires and they will have to be swapped out before the Winter weather hits later this year.

 

[Joker328]

I suspect peak dry grip is probably somewhere below the recommended pressure as I imagine Ford increases it to improve fuel economy and provide an extra margin of safety for the rims on shitty roads. Also, they are set for gross weight, which is probably a good deal higher than your DD weight. You'd almost certainly get some better traction from a stop and in a straight line with lower pressure. Lateral grip would prob be improved as well, but it could go either way since the tires would be more prone to rolling laterally at lower pressures (would be speed dependent as well). Another consideration is wet performance and hydroplaning resistance since underinflated tires can be more prone to hydroplaning (dangerously so in come cases).

 

[2Cool]

Came from dealer with 44PSI front and rear; pseudo warm. I left it that way.

The pressures when picked up from the dealer are most often laziness, not running the full PDI checklist and lowering them down from shipping pressures. When truck or boat shipping a vehicle the tires are aired up higher to make them transport smoother, sometimes aired up after strapping to help lock them in place. It is NOT done by the dealer to optimize handling.

 

[commonplatypus]

I run stock pressure. Rollover tests from autocross has taught me slightly higher will help with preventing rollover, but that isn't really a problem on the street. 39/36 is where it should be.

 

[Intuit]

The pressures when picked up from the dealer are most often laziness, not running the full PDI checklist and lowering them down from shipping pressures. When truck or boat shipping a vehicle the tires are aired up higher to make them transport smoother, sometimes aired up after strapping to help lock them in place. It is NOT done by the dealer to optimize handling.

Makes sense... the higher pressure should help lengthen the amount of time it will take to "flat-spot" a tire... which was a problem with a FoST that I test drove.

Thanks for the info 2C.

 

[DP03]

I run stock pressure. Rollover tests from autocross has taught me slightly higher will help with preventing rollover, but that isn't really a problem on the street. 39/36 is where it should be.

What he said.

 

[me32]

Im running 42/39. Runs smooth. To mention all tire pressure needs to be run cold not hot.

 

[Capri to ST]

Im running 42/39. Runs smooth. To mention all tire pressure needs to be run cold not hot.

Good thing to point out. I'll put this in the OP.

 

[dyn085]

Im running 42/39. Runs smooth. To mention all tire pressure needs to be run cold not hot.

This is what I run as well. I tried going higher but the ride was intolerable to me. I always run the maximum pressure that's comfortable to me.

Sent from my SM-G930V using Tapatalk

 

[me32]

This is what I run as well. I tried going higher but the ride was intolerable to me. I always run the maximum pressure that's comfortable to me.

Sent from my SM-G930V using Tapatalk

I agree..and different tires will also decide the pressure that works best.

 

[caliboy15]

I run 36/34

I'm in Houston and we have a very very very shitty cement roads. If I go higher my car will self destruct

 

[Intuit]

If there are a lot of pot holes and craters, higher pressure should help prevent damage to the wheels at the expense of ride-quality and circumstantial stability.

 

[caliboy15]

If there are a lot of pot holes and craters, higher pressure should help prevent damage to the wheels at the expense of ride-quality and circumstantial stability.

Id rather have a damaged wheel than a damaged spine!

 

[ericr]

The factory pressure recommendation is high to protect the rims because of the low profile sidewalls. Optimum pressure for cornering loads on these tires, and others, is typically lower. Here's a nice relevant article.

The factory is right in suggesting higher pressures. I have a set of 215/40x17 Advan AD08R's in which the recommended pressure is 32 HOT. That's about 28 cold. I bent a rim on the street because of this low pressure. When shopping for 40 series tires, pay attention to recommended pressure ranges. In the case of the Advans, 39 cold makes them feel greasy.

 

[Brickell FIST]

http://www.motorsforum.com/toyota/maximum-tire-pressure-a-police-perspective-168927-.htm

Another perspective

 

[FORZDA 2]

The best compromise I've found for street use that results in both great handling and the OEM pressure monitor allows it is 36frt and 33 rear, cold before driving or direct sun heating.