Than go by the reading of the side in shade.

 

First off, you have to remember that the “correct” tire pressure depends completely on which tires you're running. The door sticker on any car has reccomended tire pressure for the tires that came with the car from the factory. Along the way, many people switch to different wheels/tires, changing brands, sizes, profiles, etc. Each tire manufacturer has weight, speed, and other ratings on a specific tire. Your “correct” tire pressure should be based on the weight of your vehicle (ideally measured at the front and rear of the car), and the weight ratings of the specific tire you’re using. Many tires have the same ratings, so psi will be the same, but going to a more “performance” rated tire may change the ideal psi.

 

If tire size is as car specification calls for, then tire brand does not affect tire pressure.

 

The engineers at the car factory decide the ideal tire pressure. That's why they get paid big bucks. This is all based on very scrutinized mathematical calculations. It is all based on the weight of the car, the suspension and 350 other factors... Take a close look at the tire pressure recommendation from the tire company. They only give you a maximum psi. Usually around 44 psi. Regardless of which tire you buy, use the tire pressure psi you see on the placard inside the drivers side door and you will be fine.

 

Believe the temp on sticker is starting pressure when car hasn't been driven, and doesn't matter if 0 degrees or 100 degrees. The pressure in tire will already have adjusted based on the outside temp. So in winter 32, in summer 32. You have to fill or release as needed. I've never had problems triggering any TPMS doing this. Summer 97 degree temp, starting at 32, never goes more than 35.

 

Really, the bottom line: run the tire at placard pressure, or slightly above.

But absolutely do not run tire pressure lower than placard pressure. Underinflation is the predominant cause of premature tire failure, especially at high temperatures, high speed, and heavy loading.

And when tires fail in an SUV, rollovers happen far too frequently.

 

To keep my RX tires at the correct pressure I have found the Dewalt DCC020IB Corded/Cordless Air Inflator gets the job done easily. Powered by any Dewalt 20v battery or an included Cigarette lighter 12v adaptor.

 

I have a lot of DeWalt 20V tools. That inflator might be my favorite.

 

Correct, but many people opt to get after-maket wheels and tires that fall outside of the manufacturer’s specs. As you said, the propellor heads run all the calculations based on weight and other factors, The OP states that 2 different Dealerships gave her a range difference of 8-psi, which could make a huge difference in handling and tire wear. I 100% agree that stock tire sizes shoud just use the reccommended pressure and not try to “second guess” based on moving variables like ambient/pavement temperature, elevation, or whatever may sound like a good idea at the time.

 

I would say that very few Lexus owners would want to have after-market wheels. The wheels that came with the car are just fine. Prove me wrong.

 

I fill my tires to 40 cold and 45 psi hot, at the manufacture recommended psi my cross climate 2's (size 235) would get horrible mpg and also my tires would wear on the outsides, such as camber wear on both sides far faster than the middle.

https://www.telletire.com/tire-wear-patterns/
"wear on the sides"
Both sides of my tire would be a bit less than 4/32nds and the middle would be at a fresh 6/32nds

It was really weird, thought it was alignment but while getting an alignment at a private shop they said alignments within spec and to try inflate the tires to around 45 psi. Tire can handle it without an issue and solved my tire wear issue. Alignment tech says he sees this kind of tire wear a lot more recently on newer cars since cars are getting heavier and manufactures are using the most pathetic skinny tire size to please epa regulations for ever demanding mpg increases. To combat the weight of the vehicle only thing you can do is inflate the tire more till you find a sweet spot or buy a wider tire and inflate it less. More wear on sides is from under inflating a tire, now if the middle was to wear out faster it would be over inflating them. The true size of the tire imo is 255 minimum, where at 33 psi you would have uniform tire wear.

 

How's the ride at 40/45psi? My CC2s are showing more outside wear at 37K miles and I've generally run them at 33-35 psi.

 

To be honest it not too much rougher, just on potholes going slow you feel the tire rebound harder. Going +30mph you dont really feel a difference. The cc2's are an expensive tire, and my first set only lasted around 35k miles before they refused to evacuate snow from the side tread sipes which made them kind of useless in the snow. Sucks as the middles had plenty of tread, my current set at 45 psi is at 55k miles and 6/32nds given 80% of my commute is highway miles. For my next set Im planning on getting them in 265/50/20 and running 33psi and see how they wear. But 265's are 5 pounds heavier than the 235's so mpg will suffer and 5 pounds of rotational inertia will definitely wear the suspension and brakes at a more accelerated rate.

 

I just checked my tires, much more wear on the sides, I increased the pressure dramatically.
Thx dannn

 

How much did you put the tires at?