NyCrAzY

I have BF Goodrich Longtrail tires on my 1999 RX300 ... I know the door pannel says 30 psi for front and rear ao how come nobody usually uses that?

Mine is at 38 psi and the car feels heavier when driving so whats the beat option?

How much difference does it make in gas MPG?

2002RX300

As long as you keep the OEM size, go by what the LEXUS Japanese engineers say on the door jam 30PSI cold (F)(R), who would know better than them? After driving a couple of miles the PSI will increase within the tire by 2-3 pounds, as well as 1-2 pounds when hot outside.

My local LEXUS dealership always inflates to 35PSI which I always felt to be overinflated and giving my RX300 a harsh ride, plus no noticeable MPG improvement. I also get the best even tire wear as well, when inflated to the manufacturers specs.

hypervish

The number on the door jam is for the factory tires.

I have crappy Goodyear Wrangler HP's on, and I'm running 38 psi. When I had Michelin Symmetry's I would inflate to 40, and I got excellent MPG, since they were low rolling resistance tires.

mckellyb

The BFG A/T's on my wife's car are at 38, and it feels pretty good.

The tires don't 'fit' the car's look, but it's unstoppable at this point.

OEM recommended pressures are for OEM tires and are a compromise of handling & comfort. I don't like the feel of tires which are soft, however.

01rxwhite

The OEM tire that came on most earlier RX's were Goodyear Integrity's, which is a soft tire (to me). I think Lexus was going for the soft 'luxurious' ride with the 30psi thing. I have been running 32-34 psi COLD for years and like the handling and performance. Generally, the higher the PSI in the tires, conventional wisdom says you get better MPG, due to less 'rolling resistance' with the road. There are many variables as to whether any particular vehicle would actually see better MPG results. Some are- tire tread pattern, alignment, shocks, not to mention engine related & driving habit MPG items. I'll offer this bit of conventional wisdom... yes, more PSI should increase your MPG some versus less MPG. How much is up to you to observe and document. Also your benefit may also depend on whether you have a FWD or AWD RX model. So, I say air it up to 35psi COLD and be careful to exceed what the tire manufacturer says the tire can handle or you may end up with tire issues or slipped belts on the tires which could make you get worse MPG.

2002RX300

No. The placard on the door jam is definitely not for just the factory tires. The vehicle manufacturer, not the tire manufacturer, determines the correct tire pressure for the tires on your vehicle.

hypervish

No. The placard on the door jam definitely is just for the factory tires. lol

Whatever floats your boat, if you want to keep 30 psi it's your prerogative.

2002RX300

In your case, I guess "Ignorance Really Is Bliss". But if you want to convince yourself that every country in the world that imported the RX300 uses the same factory tire, feel free to do so. I was just trying to convey to the OP that the weight and load of the vehicle and it's manufacturer defines the PSI of the tire, not the tire manufacturer.

In actuality, with ambient outside temperatures being higher now than the 70ºs F and a few miles driven, my COLD PSI of 30 would be 34 and your PSI would be approximately 42 (assuming you gauge the pressure of a tire's PSI COLD)! Not prerogative, physics...