xRYD3Rx

F sport front tires are recommended 35 PSI ; Rear 36 PSI

Inside vehicle when pressing "DISP" shows front 39 and rear 40...
Question is will there be any issues as in MPG and rough driving?
or a few numbers high won't be a big prob?

dchar

The TPMS on the car isn't too accurate, but good if someone wants a general idea. Still better to get a gauge and put it on the stem for best results. You're probably pressing DISP to look at the tire pressures while you're driving, which would increase the number due to warmed up tires. If that's your cold tire pressures, then that's too much and you will definitely feel a difference in ride quality. I've even seen some users put a few below 35 and 36 PSI to get a slightly smother ride. I think by having overinflated tires, you may wear out the tires faster.

ItzFilyO

I put 35 psi cold all around and I've seen them go up by as much as 40 psi all around when driving it for a while.

I have the digital tire gauge and it reads 35.5, so the car's TPMS is quite accurate actually but sometimes it displays different numbers for each tire, usually 1 psi difference and it changes as u drive. I'd say u'll feel a slight difference when going from 32 psi to 40 psi, but the car's suspension system is so good so u won't feel it that much.

xRYD3Rx

I have a digital tire gauge as well and it reads 35/36 .. but not sure why car shows 39/40

Boomin

i use analog and at 35 but in the car it says 38-39

LexRuger

Tire pressure is very sensitive to temperature. The best time to check or inflate air is in the early morning because that's usually when it's the coldest. If you inflate the tires on a hot day to 35 PSI after you've been driving, they may drop to 32 or 33 at night or morning.

Nitrogen filled tires are supposed to be less sensitive to temp changes but I've never tried it myself.

ItzFilyO

In a cold morning mine drops to 34 today. It's hard to get the exact reading cause temp. keeps changing and by the time u get to the gas station it'll change again.

neegroy

iTrader: (19)

cold start of for me is around 36-38 and after i drive alil 40-42 mind you im on 235/35/20 and 285/35/20

bclexus

I use a digital tire gauge and I'm very picky about tire pressure. I find the TPMS sensors are right on the money.

When I tweak my tire pressure I'll go through a process of steps. I'll add air and bring the pressure up at least 2 psi above my ultimate desired cold tire pressure. I'll let my car sit undriven in a dark garage for at least 12 hours and adjust/tweak the pressure down to my desired psi using the digital gauge. My TPMS sensors always match the psi I set using my digital gauge...or at least within .5 psi.

Keep in mind that the sun (or UV) shining on tires (or one side of the car) will increase those tires' pressure by 1 psi or more. And, driving just one or two miles will increase the tires' pressure by 1 psi. Also, you should take into consideration what the temperature is at/in the location where you adjust/tweak the tires (e.g. in a warm garage) versus what the expected outside ambient temperature range will be - because compensation and adjustment for that difference should be made.

Pages 2-4 of this should be helpful Lexus Tire Inflation Pressure Compensation and Adjustment

ItzFilyO

It's 100 degrees today in Cali and my tires went up from 36 to 41 front and 37 to 42 rear when driving on the freeway. It went up by 5 psi all around.. damn!!

bclexus

I don't doubt that. If you inflated your tires [cold] at say 55-60 degrees and the ambient temperature goes up to say 90 degrees - that will increase the tire pressure by 3 psi. Throw in another 1 psi increase for sunshine, and another 1-2 psi for heating up due to driving - and you have at least 3+1+1 = 5 psi increase above the cold tire inflation you set.

The key is to set your tire pressure for the absolute lowest temperature your car will encounter when it is first driven, which at this time of year in the spring/summer will be the lowest temperature your car will encounter during the night before you get in it to first drive away...especially if the car is parked outside. From that baseline cold temperature (from having sit overnight) all future events for the day (temperature rise during the day, sunshine, heat from driving, etc.) will increase the tires' pressure.

faifai83

Have you tried resetting the TPMS?