MustBeTL

Seems like my TL's tire pressure is never right. Usually they will be somewhere along the lines of 33's and 34's. Today the outside temp got into the 60's and the pressure was up into the 37's and 38's.

Does anyone's tires stay the exact same in relation to each other? For instance, the fronts stay at 33 and rise with the temperature ,and the rears at 32 and rise the same?

Or do yours sort of dance around a few pounds here and there?

yakuzapop

Its changing all the time....
It changes depends on the temperature as well.
I think around 30 psi is ok...

Will Y.

Measure the tire pressure with the tires COLD, i.e. driven less than a mile in the a.m.- that's when the tire PSI should be set.

After that, ignore any fluctuations. PSI will increase as temperature increases, both ambient temp and temp of the tire due to friction during driving.

Set the cold PSI to at least the minimum stated on the driver's side door jamb sticker- 35F/32R for 6M, 33F/32R for 5AT. You can increase the PSI, up to 40 lbs. max, to adjust the feel of the car.

stillhere153

iTrader: (1)

I drive hard so I am set to 34 psi all around usually i read 37 or 38 psi on the mid... digital gauge in the mornings read 35 or 34 depending on the temp

vinnier6

iTrader: (1)

i have an auto, and mine says 35f/32r

korrupted

mine is 35f 32r at 50 degrees

Tripnbeats

35 all around up north..... 37-39 depending on where im driving otherwise.

acuintegra

I don't even bother with reading the TPMS... I find that it's not even accurate.

Will Y.

Sorry, I forgot to say 6M and TL-S have a factory recommendation of 35F/32R.

FWIW, my TL is at 36F/33R, although it has 32F/32R on the door sticker.

princelybug

iTrader: (16)

My MID often indicates a 1 psi difference in tire pressures, even though I am fanatical about having exact tire pressures all around. My compressor and my digital tire pressure gauge always read the same, but the MID is often ~1 psi different. BTW, fwiw, my settings are 40psi/37psi, F/R.

daveybl

The air pressure in your tires is also a function of temperature. As a general rule, the pressure will increase 1 psi for every 10 degrees F in temperature. So if you check your pressure on a 40 degree morning, and then things warm up and you're taking your car out for a spin on a 70 degree afternoon, you should expect to see your tire pressure about 3 psi higher than when you set it.

leedogg

use nitrogen if you want consistant psi's

KeithL

I have had a few 3G TLs and find the TPMS extremely accurate. First measure them cold (sitting at least 3-4 hours) preferably in a garage where the temp might be say 60ish all year round. I set my tires to 35 front 38 back (Type-S) and they are spot on, now after driving or sitting out side various times of year they vary by 4-6 psi, but every day when I start out in the garagre they are always the same 35/38. roughly every 10 degrees will effect psi by 1psi.

kenny5

I set my tire pressure according to mfr recommendation 33/32 (f/r), and the MID is quite accurate. Higher pressure gives a more "jumpy" ride, particularly over highway expansion joints, which I dislike.

alextclam

I have an auto TL-S and my PSI is 35F/34R after driving a couple of miles. What kind of results will I get if I bring the rear down to 32?

lldknyll26

My psi is 45/42. A bit too high?

Bearcat94

^^^

Uhhh.... YEAH. Especially if your running the MXM4 tire. Their MAX cold pressure is 44 psi.

When cold I find my MID TPMS to be within a pound. Usually I've got 2 dead nuts, and 2 off by a pound. Sometimes they are all right - I guess, maybe those two are actually off by ~1/2 pound, but it only shows whole pounds.

Anyway, I've got my '07 TL-S set to 34 Front /37 Rear (yes, that's correctly typed).

Will Y.

Is that your COLD pressure (measured with gauge, or MID before driving more than a mile)?

Generally, lower rear tire pressure will reduce understeer (plow) in our FWD cars. You may not notice this until you are driving on a track or close to the limit.
The lower tire pressure may also soften the ride and impact harshness, but at the expense of stiffer sidewalls/more responsive steering feel. I don't know if many people can tell the difference between tires at 34R and at 32R in normal street driving, though.





But seriously, yes, I think it's too high for street driving. You will likely get excessive wear in the center of the tread, particularly on the fronts. I don't know if you have impact harshness or a jiggly ride, but bringing the pressure down to 40F/37R may make the car feel "softer" and maybe less edgy.

alextclam

That is my pressure after driving more than a mile, measured with a gauge (MID reads the same). So, I assume the cold pressure would then be about 2 PSI less (33F/32R). If that's the case, the rear would be good but the front could probably use an additional 2 PSI. Does that sound right?

And that brings up another question, if less in the rear reduces understeer, then what does more in the front do?

Bearcat94

I'm not sure if I agree with this. I thought I did and I know it's the "conventional wisdom", but I went to an SCCA event a while back and here is how one the local pros described it:

On a *single tire*, when you increase tire pressure, the amount of tire in contact with the road gets smaller. Not side-to-side so much, that's governed more by the width of the tire/tread (235, 245, etc). But the contact patch gets narrower front-to-rear.

So if you increase tire pressure at the back of the car, you have reduced the amount of tire in contact with the road. The less tire in contact with the road, the more likely to lose traction.

Therefore, if you want to reduce understeer (or induce oversteer) on a FWD car, you put MORE pressure in the rear and less in the front. Reduce the amount of rear tire contact and increase the amount of front tire contact.

Made sense to me; day-to-day driving pressures within reason of course.

Ran 36 F / 43 R at an AutoX last night and the rear was just a little bit twitchy "at the limit". Never had that before.

MustBeTL

Thanks for th responses so far everyone.

I also tested with a old school tester that shoots the stick out and it read 33 in the fronts, and 32 in the rears. The problem is that the tires never seem to be in the same spot. For instance in the morning I may see them at 33 in the front left 34 in the front right
35 in the rear left, and 34 in the rear right. Then they dance all around. Next day they are a few up, or down.

What is considered a good temperature outside to test the cold temperature at? I am in CT and the temp has danced from the high 30's to the mid 60's so that can definitely be the reasoning.

Just want to be sure the tires aren't all different so I get uneven wear. Think I'm gonna plan to get a better gauge, do the cold pressure test and even them up to 33 fronts and 32 rears (2008 Base TL), and then see if the TPMS is more accurate. I'm not a huge fanatic on it being dead on so it won't bother me as long as I know the hand held reads accurate and I know the right amount is in the tires.

I still say if they are going to put a system like this in the car, they should spend the money to make it as accurate as possible, or don't bother putting it at all

Bearcat94

^^

The cold pressures will dance around some, especially this time of year, where one morning it's 60* and another it's 45*.

Here's what I do. I know my guage is *very* close to the MID - like I said before, within ~ 1/2 pound. So, whenever I use the car the first time for the day or after it has sat for a good long while (3+ hours), I'll see what the MID says.

If all the pressures are close to where they should be (with ~1 PSI), I let it ride. If they're off, I'll keep an eye on it for the next day or two. If they remain off, I go adjust them.

Good news is, with *warmer* weather coming, cold pressures will increase. So adjustment is going to be letting a little air out. You can do that in the garage/driveway; no need to go looking for air.