Lexus recommends 33 psi front and rear. My Michelins were at 34 when I bought the car. I upped that to 35 for a road trip over the weekend. But the ride didn't seem as smooth so I'm thinking I should let some air out the tires. How low would you go (if at all)?

 

Aptosuser, take a look at this thread for some recommendations. I believe I read 33 is best for Michelins from another member who had them. Don't quote me on that. It might take a bit of experimentation to find what works best for you. Personally I like to go a little higher (34), But I'm not the best person to ask since I have a different suspension.

 

Thanks. I had 'em at 35 but the ride was a bit rough, so I've taken them down to 34 and have seen an improvement in that department.

 

I found the tyre placard's recommendation for 230 kPA, which equates to roughly 33 PSI to be the ideal compromise. When pressures were set higher, the ride quality degraded noticeably, to me.

Interestingly, when I checked the owners manual, I see that the Lexus can come with various wheel/tyre sizes but ultimately, the tyre pressure recommendation is the same for all the wheel/tyre combinations from the factory.

 

Just keep in mind that the higher pressures also typically relate to increased fuel economy as well, which is only one more perspective to keep in mind in the overall issue.

(Being an engineer, I always think in terms of "procedures", so please forgive me if this rest of post seems too tedious for you).

Personally, I set the tire pressure such that I get even tread wear across the face, and that precise value will vary based on tire brand, road types (level and straight versus hilly and curvy), your personal driving style (aggressive or miserly), amount of load your carrying, weight distribution (front to rear), and even the type & condition of the roads (old rough asphalt or new and smooth concrete).

The way I determine the pressure setting is as follows:

1) Drive until the tires get to temperature
2) Pull slowly over the dirty/dusty concrete at the filling station
3) Get out and look at the dust pattern on the tire face --
a) If the sandy-dustiness is right at the edge of the tire where the tread starts rounding over, and only a few grains of sand are sticking to the rounded edge, I leave it as is.
b) If, on the other hand, the sand is wrapping the tire tread shoulder, I put more air in.
c) If, on the other hand, the sandy dustiness is more than 1/4" in from the tire shoulder's rounding, then I let some air out..
d) I use repeated filling station trips to make this evaluation until I get the air pressure balanced to create what I describe in "a" above
e) I use the above procedure separately for the front and rear.