The car specifications ask for 39 psi pressure for 245/40 R19 tires. Is it ok to run lower tire pressure to get a smoother ride?
If so, what is the minimum tire pressure you would recommend?

 

Check out the inside of the driver side door. Will have all specs listed on the sticker. The recommended psi is 33-34 if I remember correctly.

 

does it say 39psi on the door jam? i am not aware of a 19" wheel sedan fitment, only 17/18" where ~33psi is spec'd. perhaps double check your information. 39psi for factory passenger car inflation seems high, specifically for the g37 model line.

 

I have the sport coupe with the 19s on it. my door jam says 35 PSI.

 

lower tire pressure will not give you a smoother ride. i don't know who or why someone would recommend this but, the lower the tire pressure the harsher the ride. in addition the lower your tire pressure the tpms sys will also trigger a low air pressure fault in the cluster.

 

How does lower tire pressure result a in harsher ride?

To the OP, where are you getting the 39 psi from?

 

Lower tire pressure will reduce tire input of harshness but will do nothing for springs or dampers that are harsh.

 

The TPMS light turns on at 26 PSI or lower.

If the ride is too harsh try 30-33 PSI or when the tires wear out get tire with a softer side wall or "touring" type tire.

 

lower tire pressure results in diminished handling and responsiveness by wheels and tires. by harsher ride i am referring to overall ride quality. original poster stated he is riding on 19in rims which probably means sidewall aspect ratio is probably 45 or lower. with lower air pressure it will result in less dampening by the tires as air in the tires help with ride quality especially when you hit cracks, small potholes, and other bumps in the road.

 

Whats a good tire pressure for 20s staggered- 245/35/20 front -275/30/20 rear

 

As odd as it may seem, the vast majority of wheel/tire combos all want pretty much the same pressure -- 32 to 36 psi. The variability is your comfort sensitivity and your compassion for your tire's shoulder.

 

I just put new rims, tires and TPMS on my G, initially the guy who mounted the tires on the rims says he filled it with 33 psi. which was recommended inside of my driver door. Anyways, I had no warning lights on for a couple weeks. Now all of the sudden , I'm getting the low pressure light. I actually inflated them to 36 recently, lights still on. weird right ?

 

Do you get the low pressure message in the center screen? Does the light flash for the first 30 seconds (or maybe minute, can't remember) then go solid on for the rest of the drive? If so your TPMS isn't synced to the car, takes a few days of driving for the car to throw a light up. When I switch to my winters without TPMS it takes a few days of driving before the light comes on.

 

When it was done initially it worked fine, the light came on maybe 2 weeks after the install and yes it blinks and stays solid in the center console I'm sure these were auto syncing , maybe I should deflate the tires and refill

 

Firestone or discount tire has that machine that they reset/sync tpms to car- it takes like 5 minutes to do