luxury1

I have put 39 PSI into my LS all around. I like the way that it handles and it gets a little better gas mileage but this is higher than the sticker suggests. Are there any serious drawbacks to this especially as it relates to safety, stopping distance, etc? Also, will the center of the tires wear out much quicker at this level?

Johnny

You will find it easier to do 360s in a parking lot...

If you're just driving at city speeds, it shouldn't be a problem. At highway speeds however, the tires bulge out from the centrifugal force applied, and tire wear will increase, especially on the steering tires. You will "marginally" lose some traction going around corners though. So it really depends how you use the car. You're certainly won't get any blowouts or anything like that.

19psi

it will be fine. you may not even notice any additional wear, as you're really not that much hihger than recommended.

Mike_TX

If you are talking about 39psi COLD pressure, keep in mind it will rise to maybe 43psi or so in hot weather or after driving at freeway speeds for awhile. That puts it near the maximum pressure for most car tires, and that's not a safe place to run your tires.

OTOH, if you're talking about the tires reaching 39psi after driving for a long time, that's not overly excessive - especially in the summer - although it's a little high.

Excessive tire pressure will cause abnormal wear and will affect traction. I personally think it's a good idea to follow the car manufacturer's recommendations. You aren't going to save any meaningful amount of gas doing this, and you may be endangering yourself.

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CEOEngr

I too firmly believe in following the manufacturers recommendations. However, I am puzzled that when either of our lexus goes in for service it always comes back with 41 psi. I have questioned the SA, but his response has always been " Ahh ahh that shouldn't be.... let me have it checked again". I guess they have the rookies working the tire detail.

luxury1

Thanks for all of the responses!

It is a cold PSI so you are right, it will rise.

Lexus delivered the car to me with higher PSI than suggested (38) so that is why I thought it was probably safe to take this approach but maybe I should take it down just a touch.

rominl

iTrader: (4)

actually, lexus delivers cars with higher psi so the cars are easier to roll, etc... at the port. BUT the dealerships are supposed to check the pressure AND correct them back to the spec.

39 is ok, but for stock 18s they are way high and not necessary. you are mostly degrading the ride

Atlas

Yeah, the Lexus Dealer did not reduce tire pressure after it was delivered to me. I was driving and I thought the ride was harsh, I was scrolling through the display and saw the PSI was 39. The next morning I reduced the PSI to 33 PSI, the manufacturers recommendation....BIG difference, ride much smootherat 33.

Dave Mac

The dealer replaced my wheels with chrome wheels and still delivered the car to me with 40 psi as they do after each service. I notice the ride right away and reduce the pressure down to 33 the next morning.

Dave Mac

19psi

the reason your cars always come back with higher thatn "recommended" pressure is because the techs know that recommended pressure wears out the edges of the tires more. yes it rides better butyou'll be wearing out tires faster.
the heavy weight of the car puts a lot of pressure on the edges of the tread during cornering. more air pressure helps to keep the tire from deforming and wearing badly.

timeToy

iTrader: (11)

My LS460 come from the dealer with 40-41 psi... After reducing to the recommended pressure, I feel it drive much nicer !

Nospinzone

You should be OK with 39 psi in PA (its not like you'll be driving there at sustained speeds of 90 mph in 100+ degree temps!)

It will give you a harder ride, but fuel economy and tire wear will improve slightly. Check the wear regularly. If you are overinflating the tires, they will wear in the center more than the edges.

Craig B

The reason the dealer stores cars with high pressure, it reduces flat spotting the tires. I run 35 PSI in all four tires. You will notice a stiffer ride with more air. My car was delivered with 45 PSI in all tires. I think 33 PSI is too low.

Craig

Mike_TX

Boy, I really have to disagree with that. The mfr's recommendation is usually the best compromise between good ride, good handling, good wet-weather traction, temperature control, economy, road noise, and tire wear. Under-inflated tires DO "scrub" in turns, and therefore wear faster, but over-inflated tires actually slide sideways a small amount in turns, which also causes wear.

I've always run recommended pressures (and sometimes less), and my tires always wear evenly across the treadwidth. OTOH, I've seen lots of tires run at higher than recommended pressures and they usually show accelerated wear in the middle of the tread.

I guess you can run them wherever you want, but just know what you're getting into when you do. Or go to a reputable tire dealer and ask someone there who knows about such things (not the grunt changing tires).

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rominl

iTrader: (4)

i disagree. at 40+psi on 18s? you are going to have center wear