CalMike

Hi Everybody! It's been a while since I've last checked in. I've been enjoying my GS F-Sport for almost a year now and just brought it in for its 10k mile service.

Until bringing the car in, I believe I was riding at about 37/38 PSI front/rear, cold start. I'm on the stock 19" wheels and original tires. I live very close to the dealership, and when I drove home, I didn't notice any difference in the ride. Ever since then though, especially on the freeway, the car has felt different to me, it feels bouncy and occasionally its handling is harder to predict. I had checked the TPMS earlier (cold start) and was surprised:

Front Left: 37 PSI Front Right: 36 PSI
Rear Left: 41 PSI Rear Right: 39 PSI

As above, the front left is now almost always 1 PSI greater than the front right, and the rear left is sometimes 2 PSI greater than the rear right, always at least 1 PSI greater. The fronts are 3-5 PSI greater than the rears (rear left is 5 PSI greater than front right). Meanwhile, the decal on the inside of the driver's door, which shows the recommended pressure for the car at cold start, states 35 PSI front/36 PSI rear. Apart from just the unevenness, that means they've got one of my tires inflated to 5 PSI more than the standard recommendation.

I can see inflating a couple PSI greater, and I can also see a fluctuation of 1 PSI between right and left as a normal possibility for even the most qualified of service technicians, especially given that the system displays integers and has to round up or down. However, I was definitely more accustomed to the ride before and am curious if the dealership inflated the tires like this for a reason. I've left a message for the service advisor who had worked with me but haven't heard back yet.

The stats above were with a cold start, I also took a photo of the TPMS after some driving once the tires had a chance to warm up (about a 3 PSI increase across the board over a cold start):



What do you think?

Mike

Rexus300

iTrader: (1)

Jeez,

You are way TOO overinflated!!! Bring the cold pressue down to 34 or 35 psi. Front and rear. You should not have to or expect the sevice people to do the pressure for you.... Get a proper digital pressure gauge and take some air out of the tires and maintain them monthly.

ItzFilyO

I set mine to 37-38 cold. Then it could go up to 40 when hot. My max PSI on my tires is 50 something and I'm still well under it so I'm good.

sydtoosic

35 f... 36 r...

LexRuger

Get them filled with nitrogen and they won't fluctuate as much.

smomin23

Look on the inside of the driver's side door jamb for proper cold inflation. My AWD F-sport is 35 front and 36 rear I think I don't remember but that's where you should be going for this info

Polo708

It's listed on the inside door jam of the driver door (b-pillar)

Christobol

Wow calm down Rexus. Go out and check your tires, and you'll see they are rated for a max pressure of 51 psi. I didn't check the min, but it's not too far from 34.

From a performance standpoint, you would need to take the car on a track and do some test to determine the variation in temps across 3 or 4 places along the width. Then optimize the pressure so it's as close to even as possible (to truly get even temps you need to adjust the alignment).

Most of the time you'll have the best handling around 40 psi.

For the best gas mileage you'll want a higher pressure to reduce the contact patch (which reduces handling capabilities as well).

To maximize the life of the tire... I'm not sure, I never cared, but I would guess it's around 34 psi.

moose66

As long as you don't have to pay for it. If you do have to pay for it, you may as well use the free air. Once filled with nitrogen you should not have such drastic fluctuations. If once you fill with nitrogen, you still have issues, you may have a bad valve or two.

Rexus300

iTrader: (1)

I agree with you. However, my tires are maxed for 44 psi and they are the michelin mxm4 tires i have gotten last year and they give such a smooth and comfortable ride on my f-sport and i am happy with the long tire wear. I already put 20k on them and still have 70 percent left tread. The handling is still excellent at 34psi cold.

sarmyth

That's funny.


I'm currently running at 40 front 42 rear cold, to try and even out my tread wear... dealer let down my pressures to 34/35 and I didn't catch it for a couple months.

I typically run 38F/40R cold which keeps my outside shoulders from wearing down too much quicker than the center.

Afrosheen

Mine are currently at 39-40 warmed up. During the super winter we had here earlier this year, they were at 35 warm and anything below that would set off the alarm. Pretty annoying to have the alarm go off in the morning then get quiet in the afternoon, every day. So I just leave them high-ish and won't have to worry about it next winter.

jtrue28

You all realize that air is 78% nitrogen, right? Green tire caps are the biggest scam this side of Nigeria.

LexusGSFGO

You should specify whether your talking about AWD or RWD, as the former requires lower air pressure.

coach1

FYI...Yesterday the weather cooled down and I got a low pressure warning light. When I got home I inflated the tires to around 33 psi which is where I'm running these crappy Dunlops. The warning light would not reset...damn. Got the owner's manual out....went online and could not figure out what the problem was. Manual said take it to the dealer...double damn. Checked the dash read-out and it agreed with 33 psi accept one rear tire had a yellow highlight. So I inflated all the tires to 37, the warning came off and I adjusted the pressure down to around 34.