tire pressure questions
 

What tire pressures are you guys running on stock setup?

At what pressure does the TPMS light come on?

Can you set what pressure you want the light to come on at?

1. Refer to the label on the drivers door jamb

2. 29psi if I remember right (that's sort of a guess) , it's in the owners manual

3. No

TPMS thresh holds can also be altered in the Techstream. .......the previous owner of my car had them set at 26 psi. Not sure what the maximum tolerance is for this?



Digger08

I know that 36 is manufacturers suggested psi - i was wondering what you are all running instead - i usually do 35 psi

I'm running 40 on the front and 34 on the back. It was the recommended tire pressure for grip and tire life by the race alignment shop when I had my alignment done. I was just gonna do 36psi all around, but when I went to their shop and saw them working on a 69 mustang and a murcielago. I just stick to their recommendation. Haven't tested it yet in the canyons and track.

Not using recommended tire pressures can lead to uneven tire wear and/or accelerated tire wear and/or decrease in fuel economy (I know that last one is very important to many of us) it's on the door for a reason.

But if you want more grip, run it slightly lower...or better yet, just buy better tires.

Also, unless you have a very high grade tire pressure gauge, you won't know the difference between 36 and 35. I believe our TMPS light comes on at 30psi

I am running 35 in the front and 37 in the rear...recommended by my shop. Who knows...

I am running 32 all around... Feels fine for me

It varies for different types of tires. My NItto Invo's which had relatively soft sidewalls did best at 40psi. I'm currently on Michelin Pilot Super sports are the fee very floaty at the same 40psi. I have since brought them down to the Lexus recommended 36psi (as noted on the label on the driver side door) and feel great at these pressures...Darshana S...

The TPMS light should come on if the tire pressure falls below 78% of the set point.

My tpms light went on a few days ago and my pressure was ~28 psi. I just reinflated to 36 psi.

I run 38psi all around, but thats on aftermarket wheels.

I figure it is easier adding to this thread than starting a new one.

I just finished a VDI (Vehicle Dynamics Institute) driving course...on road, off road, and vehicle combatives. They taught that vehicle manufacturers often recommend tire pressure levels lower than optimal (efficiency&safety) for ride comfort reasons.

They recommended that you fill your tires to 90% of the max tire pressure listed on the tire sidewall (as long as that is higher than the auto manufacturer recommendations).

My Michelin PSS tires have a max pressure of 50psi, and 90% would be riding around at 45psi front and rear (9psi more than recommended by Lexus). I am trying this out now. The ride is a little firmer, but I haven't pushed the car to see if I feel a different level of grip.

What are your thoughts/experiences on this?

I run 44 psi hot in the Bridgestones which turns out to be 32 psi cold. I haven't tracked the PSS yet, but I suspect they'll be similar. However, pressure on the track is very different from pressure on the street. If you want a simple and practical way to check pressure, put white shoe polish stripes across the tread, drive the car as you normally expect to drive it, and adjust the pressure until the white stripe goes away across the full width of the tire.

If you pumped up your tires as high as these guys are recommending on the track, you'd think you were on ice skates after 3 laps.

I would stick with 36 cold as recommended by Lexus. Too high and you lose grip and have uneven tire wear, and to low your going to burn up the tires . If your on a track you have to check and adjust. They can go way too high.

Thanks for the comments. I've never had an issue running 36psi except for one gouge on one of the wheels when my wife pinched the sidewall entering a driveway too fast. I imagine running a higher psi will help avoid pothole flats a little, but I don't want to lose grip.

BTW, if I tried the 90% rule with my truck tires, I would be running 72psi!!! As it is right now they are at 42psi and don't bulge at all with 2000 lbs in the bed...they are Kevlar lined though and have much stiffer sidewalls that the stock tires.

I run 35 psi all around still curious to see what others use

I run 33 psi hot all the way around, I found in the owners manual that you can set the pressure on the TPMS, Im not sure what page but it is in there and I did set mine. With it being almost midnight im not gunna go out to my car to find out for sure, but i do know the info needed to reset the TPMS is in there.

I also run 35 psi on all 4. No problems!

Hot? Like after 10 laps on a road course hot, or just drove awhile on the freeway hot? There is a huge difference.

I set mine cold - at 37lbs. for all four corners.

Lou

The other day, TPMS light went on. Went to the gas station to fill up on air. Realized front right tire was running on around low 20s, which was surprising. All other tires were at 30 psi.

Is this because the IS-F has "pulling to the right" issues?

^^^^Sounds like a slow leak:uh: If you drive to the gas station for air, you do realize your heating up your tires, right? And you can't get a good cold pressure reading. Better to have a compressor at home and fill them up cold.

Lou

I've played around with air pressures on the PSS (stock size, stock wheels) and 36-37psi cold is a good balance for daily driving and curvy mountain roads. Tried 44 psi cold as well and when the tires get heated from driving, they definitely have less traction upon hard acceleration/cornering.

I would never go below the factory recommended PSI settings on tire pressures while driving on public roads.

On the track, 36 psi cold, after a session, 44psi hot. The PSS' don't last more than 4 laps (2.8mile course, 20-30min sessions) before they lose grip and get greasy. Even after dropping the tire pressure to 36 psi hot, same issue. Due to the weight of the ISF, it really needs r-compound tires for track duty.

In conclusion, everyday driving = 36 psi. Track duty = depends on the track layout and other factors if running stock street tires.

Had 36 PSI cold, after a few laps it was 48 PSI. People at the track recommend I put it down to 38 PSI when hot. Thoughts? ? Suggestions? ?

I wouldn't go that low. I aim for 44 psi hot on a road course. It works out to 32 psi cold (air temp around 72F - 22C) the next morning.

"Spirited" freeway and "spirited" regular road driving. I did that for comfort mainly. If I were to take it on a road course I would up the pressure