dougt

My RX330 has the 17inch tires. The manual recommends 30psi in all tires , this seems low to me. What tire pressure is everyone else using?

TunedRX300

I use maximum pressure specified by tires for better handling and less wear.

jcg

By over inflating your tires you will wear the center before the outside edges of the tires. I have found this out from past experience. The overall result is that you will actually wear out the tires quicker.

I now keep about 2 lbs more than the recomended pressure - not the max pressure.

I also think that keeping the tires extra hard will cause the suspension to take a beating.

Just my opinion.

mikey00

Max tire pressure will increase wear and decrease handling. Wear will be increased due to the fact that you will have more center tire contact and very little edge contact. The center will wear much faster than the edges. The reduced contact will also affect handling. This info can be found on almost every major tire manucacturer and reatiler site. I usually run at manufactures recommendation or just 1 or 2 over.

TunedRX300

Mine always wear more on the edges, so I got more life out of my tires by inflating them at max cold. Also most drivers do not check tire pressure regularly, over 30% of cars on the road under-inflates. Putting a few more psi helps.
There is a difference in traction and resistance to roll, I prefer stiffer tires since it can reduce body roll. My RX300 has 6.2 inch of sidewall with 225/70/16 tires, if Lexus suspension can not handle few more psi, well.. they should not be shocks and struts in the first place as they are intended to take beatings for you. It is the same (IMHO, weak) argument I can made that these additional psi will protect my rims from getting damaged by rough roads, or higher pressure will help me to reduce brake pads wear since I don't have to brake as hard during corning.

HarrierAWD

30 psi is what Lexus recommends. Generally the lower the tire's load index, the higher the needed pressure. Lexus probably find 30 psi a perfect balance between load requirement, handling, and ride comfort. Put in whatever you wish, but I would not deviate more than 5 psi from manufacturer's recommendation.

I personally put 32 psi in the front simply because the front tires carry more weight. Steering response becomes more precise, though ride quality decreases slightly - I could feel a bit more road texture.

Don't forget the spare tire. I do put 35 psi in my spare tire because it loses about 1 psi per month. This way I only have to re-pump it every 6 month or so.

Lexusfreak

I use between 32 - 35 psi. Best handling, fuel economy with even wear.

parula

The 300 was about the same tire pressure recommendation but I like a firmer ride and at ~38 I find I get near perfect wear, not quite at the tire max of 44 on my great Goodyear Integritys. When I traded the '99 the tires had 50k and wear was even, not overworn on the center and no overwear on the edges at all as I recall. Same on the Honda with 60K right now fwiw with miles to go- ot. The soft cushy feel of 30psi is nice but imo the ride and handling is better with a bit more air.
Note, all my Lexus vehicles have never had an alignment either as I recall - testament to the engineering in this vehicle. (Honda maybe had 1 alignment when I had to change struts once, but I'm not even sure of that, course that was once in 19 years!)

rxdriver

One note about the tire pressure on the sidewall - it's an absolute maximum, with no regard for the amount of weight on the tire. Therefore, most tire manufacturers recommend that you do NOT inflate them to that pressure for normal operation.

It's OK to run them above the car manufacturer's recommendation, but you should be below the limit on the sidewall. The manufacturer is supposed to work with the tire manufacturer to balance the ride, handling, and weight of the car when they make a pressure recommendation.

Personally, I think the ride is great at 30 psi, but I agree that it handles better at about 32 - 34 psi.

TunedRX300

My Yoko Geolander's spec is 35 psi max cold. HarierAWD said well, even "one pressure fit all" recommendation from Lexus or tire manufaturers are tradeoffs. I don't belong to the profile of a generic RX driver, if there is a true "average driver". Bottom line, I know what is important to me and adjust accordingly.

Neil64

From my readings, you should never inflate to maximum pressure either hot or cold. Here is why: As a tire gets hot from the friction of rolling, sliding, absorbing impact, etc., the air inside gets hot and increases pressure and expands. From my understanding, as much as 4 psi in a couple of miles. Friends who have air pressure monitors on their newer high end cars tell me that they have seen greater than 5 psi increases from the time they leave their houses in the morning to the time they get to work. Granted their commutes are greater than a couple of miles but you get the idea. All of this holds true from what I have seen with my own eyes in chemistry labs and checking my own tires. Air pressure increases with heat and expands. That is also why tire manufactures advise us to check air pressure when tires are cold.

That being said, inflating to the max recommended pressure puts your tires at a greater risk of a blowout sort of like inflating a balloon so high that there is no give to it before it pops or overfilling a metal propane tank. Yes, metal propane tanks do explode from overfilling.

I am sure all of us will do whatever we can to protect our family's lives and others by making sure we have quality tires and brakes. Heck, I am looking for tires right now and can not bring myself to consider buying some highly rated Firestones. They had blowouts in the past because they did not meet specification. Sure, some of those blowouts may have been influenced by low pressure but I believe that if it didn't meet spec at the lowend, who is to say those same tires could have withstood over inflation. Plus, in my opinion, max pressure ratings are probably greatest on a new tire with the most meat on it. I can only imagine what all of the heat, friction, impact, etc. does to a tire, not to mention the wearing of the tread, etc. I guess we need a tire expert or engineer who can tell us if max pressure is calculated for the life of the tire or …….?

I was surprised to see how delicate a sidewall is. My wife barely scuffed her sidewall on a curb. Trust me, it wasn't really bad compared to some I have seen. The next day the sidewall had a fairly large bubble. I took it to two different tire stores who recommended immediate replacement. They claimed that air had gotten underneath the sidewall structure and the only thing holding that air in was a thin layer of rubber that was the bubble. Made sense to me but cost me $145 to replace what was a relatively new tire.

There are other drawbacks from inflating a tire so high such as reduced traction, poor ride quality and uneven wear.

In my opinion, why not leave a cushion of 10 -15 psi from the max. The tire factory guy could have a had a bad day when building your tire, so maybe the real max pressure is 2 psi lower than what is stamped on you tire.


Neil

dougt

Great points Neil and everyone else, I too would have trouble buying Firestone tires. I think that I will keep the tires at 30 psi and if I plan a long highway trip I may notch them up a couple of psi. I would rather burn off tires than knock the crap out of my new Lexus.

kojakrx

Dumb question, but wouldn't overinflating your tires also affect the accuracy of the speedometer, the odometer, and also the reliability of the gps unit when you are out of range (ie, in a tunnel or under a long overpass?)

TunedRX300

Tire pressure should be checked at cold. Type in "maximum tire pressure" first google link comes up:
http://www.cars.com/carsapp/national..._pressure.tmpl

mikey00

The link also explains why not to use maximum tire pressure.