Do you inflate by manual specs or tire specs?

[Quattro Pete]

Originally Posted By: HerrStig
Originally Posted By: Quattro Pete
Originally Posted By: totegoat
Tires achieve their highest weight carrying capacity at maximum psi.

That is often not the case...

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=195

And I drive a car, not an earth mover.

Who said anything about an earth mover?

Quote:
P-metric and Euro-metric sized tires' "maximum load" inflation pressure may be, and often are, different that the tire's "maximum inflation pressure."

 

[ExMachina]

Originally Posted By: totegoat
Low psi causes heat buildup, and heat kills tires.


If I head out on a highway trip during the summer, I do like to put in an extra 3 psi over the placard door-jam numbers. Fuel Economy gains and lower temperatures for high speeds. (never exceed tire sidewall max psi though, a strict upper limit)

Interesting about the tire sidewall max number: I saw some Michelin popular radials just a few years ago that had a max sidewall psi = 35 !!! Man, thats cutting it close, isn't it? So those tires do exist, oddly enough. Now when I shop for tires I look for at least 44 psi max sidewall pressure tires.

 

[stephen9666]

Originally Posted By: ExMachina


Interesting about the tire sidewall max number: I saw some Michelin popular radials just a few years ago that had a max sidewall psi = 35 !!! Man, thats cutting it close, isn't it? So those tires do exist, oddly enough. Now when I shop for tires I look for at least 44 psi max sidewall pressure tires.


Yes, as tire-building technology has improved, it seems max inflation pressures are creeping up.

Or at least more and more tires now have the higher max inflation pressures that used to be found only on some tires.

 

[Brigadier]

Originally Posted By: SHOZ
The door sticker is for OEM tires. Different tires than that will have varying handling and wear characteristics. Maybe the door sticker pressure are good, maybe not.


^^^This.

Blindly running the door placard pressure is assuming all tires are the same.

 

[KitaCam]

Still waiting for OP to respond to questions about what tires are on the Camry...

 

[Quattro Pete]

Originally Posted By: Brigadier
Originally Posted By: SHOZ
The door sticker is for OEM tires. Different tires than that will have varying handling and wear characteristics. Maybe the door sticker pressure are good, maybe not.


^^^This.

Blindly running the door placard pressure is assuming all tires are the same.

If the tire is the same size and has the same load rating as the OEM tire, then door placard pressure certainly does apply.

 

[SirTanon]

My Fusion specs 32 PSI, but I usually inflate to about 36PSI for lower rolling resistance. I drive about 90% highways @ about 70-75MPH so I feel this is the best configuration.

In summer, when I get home from work, if I check my pressures right away, they're up to about 38-39Psi due to the heat. Still within range.

 

[Traction]

Passenger tires are max load rated at 35psi, NOT max sidewall pressure even though they might hold 44psi or higher.
Good thing they are not rated for max 100psi, because some people would think that would be even better yet. I would bet NASCAR does not use max sidewall pressures. Tires are pretty much air springs connected to the road. They need to absorb bumps as well.

 

[totegoat]

From Tire Rack:

"Tire Pressure in the Rain

For both autocross and road racing, increase tire pressures 6-10 psi from what you would normally run in dry conditions. Hydroplaning occurs when a wedge of water develops between the tire and road surface. This wedge can actually lift the tire off the road and eliminate traction. Increasing the pressure rounds the profile of the tire by decreasing the deflection of the tire. This results in a smaller contact patch - narrower and shorter. It also helps keep the grooves in the tread open so they can channel the water out from under the tire."

 

[Dominic]

It really depends on the car. My Mazda 6 spec is 35psi F/R on door placard and I run ~10% more at 38psi for handling/safety/blowout prevention. It also buys me 3-6 months of driving without needing to air back up.

For my Nissan Versa it has skinny 185mm tires, spec is 30psi F/R. I run nearly 40psi in them because otherwise the ride is squishy, and the tires wear the shoulders at stock spec. I would say the narrower the tire the safer it is to go up more on psi without causing weird center-wear on the tire.

 

[ccap41]

Originally Posted By: Brigadier
Originally Posted By: SHOZ
The door sticker is for OEM tires. Different tires than that will have varying handling and wear characteristics. Maybe the door sticker pressure are good, maybe not.


^^^This.

Blindly running the door placard pressure is assuming all tires are the same.


You're supposed to put the same specification of a tire back on. Same load rating, speed rating, and size. Therefore you should still put what the placard says. Or at least start from there and tune as necessary.

 

[ccap41]

Originally Posted By: totegoat
From Tire Rack:

"Tire Pressure in the Rain

For both autocross and road racing, increase tire pressures 6-10 psi from what you would normally run in dry conditions. Hydroplaning occurs when a wedge of water develops between the tire and road surface. This wedge can actually lift the tire off the road and eliminate traction. Increasing the pressure rounds the profile of the tire by decreasing the deflection of the tire. This results in a smaller contact patch - narrower and shorter. It also helps keep the grooves in the tread open so they can channel the water out from under the tire."


Good info to know! ..I'll never chang my tire pressure to drive in the rain but still good to know..

 

[Reggaemon]

Why doesn't the Door Placard just list the tire size and for the
inflation say " Use max pressure listed on the tire"?

 

[ExMachina]

Originally Posted By: Reggaemon
Why doesn't the Door Placard just list the tire size and for the
inflation say " Use max pressure listed on the tire"?


Are you joking? Honestly I can't tell. Techie humor can go "there" sometime.
Answer: Every vehicle has a unique weight distribution, load capacity, and suspension geometry and spring rates that alter how air pressure in the tire uniquely affects handling in that specific vehicle. Therefore, no one air pressure will work best on all vehicles.

 

[Traction]

Originally Posted By: KitaCam
Still waiting for OP to respond to questions about what tires are on the Camry...

Unless they are spec rated with a V speed rating, or higher. All bets are off!

 

[KitaCam]

Originally Posted By: Traction
Originally Posted By: KitaCam
Still waiting for OP to respond to questions about what tires are on the Camry...

Unless they are spec rated with a V speed rating, or higher. All bets are off!


Exactly....my 17s are V-rated...the 15s were H-rated...some Camrys run T-rated...

 

[CapriRacer]

A couple of items:

1) The vehicle tire placard: Because tires are standardized, if you use the size written on the vehicle tire placard, then the pressure listed there is appropriate. It doesn't matter who manufactured the tire. I go into more detail here:

Barry's Tire Tech - Load Tables

2) Tires do have different characteristics and you can vary those characteristics by varying the inflation pressure - BUT - remember a) the vehicle manufacturer set up the vehicle's springs, shocks, and sway bar based on the spring rate of those OE tires and that spring rate is pretty much the same for a given inflation pressure (Put another way, inflation pressure is by far the largest contributor) and b) there are a whole lot of things that change when you change inflation pressure - some good, some bad.

Ergo, deviating from the vehicle tire placard must be done carefully and take into consideration ALL the parameters affected.

 

[skaughtz]

Originally Posted By: KitaCam
Still waiting for OP to respond to questions about what tires are on the Camry...


2007 Camry LE 2.4L

Michelin Energy MXV4 S8

P215/60R16

I believe these are OEM tires. I bumped up the pressure last night in both the front and rear tires to 35psi from the listed 30psi. Just on the way to work I noticed that the ride is smoother and bumps are less noticeable. Then, just for kicks, I took a turn at a much quicker pace than I would usually and I noticed no squeal and the car seemed to grip better.

I'm on board with the idea of going slightly over what is listed on the door sticker. Perhaps it is just a placebo effect, but the ride feels better with the little extra air. I rotate my tires with each 5k oil change so I'm not too concerned about increased wear, and I also like the idea of having a buffer back down to the 30psi threshold should it slip my mind to check the pressure in the future.

 

[skaughtz]

Also... since I can't seem to find the edit button for some reason... the max psi of the tires is 44. I read that the recommended psi on the door is the minimum pressure required to support the vehicles maximum load carrying capacity, so I can't imagine that a few psi increase will yield any real negative effects on a daily driver.

 

[Traction]

Should be fine at 35psi. It is interesting that in 2011 Camry LE specs 34psi for the same tire, and a bigger 2007 Avalon calls for 29psi. Run anywhere in that range for what feels best. Just don't run max sidewall pressure.