LexRuger

I wouldn't run anything lower than what the door says. For one, the weight capacity of the tires is decreased, and second, more stress is put on the sidewall causing flex and premature tire failure.

SW17LS

2PSI is not going to have that effect. The tire pressures on the doors are set for a lot of different reasons, one of those is fuel economy. One of the reasons you see higher pressures now than you used to is just that, the need for higher fuel economy standards. The weight capacity of the tires is not dependent on an arbitrary third party pressure suggestion which is not even set by the tire manufacturer, its a guideline from Lexus. The pressure recommendation from Lexus is for ANY tire, regardless of the brand or model or weight specification. Its simply a suggested pressure for their opinion of optimal ride, economy, handling and tire life.

I wouldn't run them 5PSI low, but 2PSI, 31 vs 33 is not going to cause any problems. Mine have run at that pressure now for about 15,000 miles and I have no adverse or unusual wear, no changes in how the car handles, bumps and such are just a little bit more muted which I prefer.

If having tires 2PSI off the door placard caused all these issues, everybody would be blowing tires all over the place. Nobody outside of enthusiasts like us has properly inflated tires within 2PSI. Hell, I've gotten it back from the dealer 10PSI high, 5 low, all the tires different pressures. 9.5 out of 10 people would just drive it like that and be fine.

lesz

The 2006 ES that I previously owned had the same Michelin tires as my 2013 ES, and the weight of that 2006 ES was close enough to that of the 2013 to make the difference, for all practical purposes, insignificant. Yet, the manufacturer's recommended tire pressure for the 2006 was 29 pounds, compared to the 33 pounds recommended for the 2013. My guess is that, for those who say that the 2013 ES has a firmer ride than did the ES vehicles of 2006 or similar vintage, any difference that they feel that they see might well be the result of the difference in recommended tire pressure. That said, I may have said earlier in this thread (or some other thread) that, unless I did a very careful side-by-side comparison, I'm not sure that I would be able to tell you which had the firmer ride quality.

SW17LS

Absolutely...the reason for the difference in the placard is fuel economy...the higher the PSI...the higher the fuel economy and the EPA tests them using all factory specs. Tire pressure has a HUGE impact on the way these cars ride...when I get the car back from the shop after a service for instance, I can immediately tell they have over-inflated the tires...even if its only a couple pounds.

I suggest anybody who is unhappy with the ride of this vs the previous ES, air down the tires and see.

Worst case scenario...fuel economy suffers slightly and tire life is reduced slightly. I don't know about you but I bought a Lexus for the smooth quiet ride, if I have to buy tires 5k miles sooner to have the best ride I can have, so be it.

LexRuger

You still have to take into account for temperature fluctuations and inaccurate tire gauges. I'm not saying you're absolutely going to have problems running a couple pounds low, but if Lexus puts the number in the door, it should be taken seriously. Tires are one of the most important pieces of equipment on a car right?

SW17LS

Its a guideline, thats all. Lesz's description of two ESs, basically identical...same size wheels...same size tires. Recommended PSI was 29...now its 33. My 2010 ES was 31 on the same size wheels and tires. Its not a question of a "safe" pressure, the pressures are higher to get better fuel economy at the sacrifices of ride quality. For instance you are running oversized wheels...do you air your low profile tires to the pressure on the door? Your tire size is not the tire size listed on the sticker...are you operating an unsafe vehicle? By your logic, yes.

To those of you unhappy with the ride, try a lower PSI.

lesz

I'm confident in guessing that the significant majority of drivers don't realize (or care) about how much temperature changes will affect tire pressure. While my GX has a tire pressure monitoring system and uses a warning light to indicate low tire pressure, my ES is the first vehicle that I've owned whose information screen shows actual tire pressures. Using that screen has reminded me of just how much a difference, say, of 15 degrees can affect the tire pressure.

I tend to pay more attention than most to making sure that the tire pressure is where I want it to be. During the transition period from fall to winter, I added air to the tires of both of my vehicles probably 4 or 5 times to account for the effects of dropping temperatures. In the transition from winter to spring in a couple of months, I'll be letting air out of the tires every couple of weeks as the temperatures increase. I'm sure, however, that there are many drivers who, even if they know what the pressure was when they last checked their tires a couple of months ago, have no idea that their times may now, with very cold temperatures, be running as much as 10 pounds lower than what they thought they were. I'm also confident that, at any given time, there are a good number of people whose tires are running 5 or more pounds more or less than what they should be.

LexRuger

Which is why I think it's safer to never inflate your tires any lower than what is recommended from the manufacturer. Fill them to 31 on a warmer day, on a colder day, the pressure will be into the high 20s. The average person isn't going to want to have to add air in these situations.

SW17LS

Its also "safer" not to deviate from the OEM tire and wheel sizes...but you did that because it suited your wants and needs. Its no different.

PSI drops 1 PSI per every 10 degrees in external temps. So...it has to drop 20 degrees in external temp to get the pressures into the high 20s if they are set to 31. Remember...we're only talking about 2 PSI. So...if its hot one day and cold the next...you're only 2PSI down from where you would have been on the stock pressures. When temps fluctuate you have to add air anyways. Even at high 20s in PSI you will be safe, you just risk reduced fuel economy and you risk wearing the tires prematurely. Whens the last time you heard about a fiery rollover on the news and the accident investigation cited slightly under inflated tires as the cause? The answer is never.

Also remember that the TPMS is designed to alert you to a difference much larger than 2PSI. So...Lexus doesn't feel a 2PSI differential is significant.

Its all about understanding why suggested guidelines are set, not just blindly following them. I find your concern about 2 PSI completely at odds with your decision to run a wheel tire setup so vastly different from stock.

gemigniani

What's going to happen if you run the 17" tires at 29 PSI (cold inflation pressure)? Nothing except a wee bit worse fuel economy and a wee bit more wear on the tire edges. The tires will still run cool at 80 MPH on a 105 degree F day in the desert. And the ride will be noticably smoother.

35 years ago Toyota Corona and Cressida owners manuals recommended radial tire pressure of only 22-24 PSI for driving all day long at up to 75 MPH!

LexRuger

More wear on the outer edges means the tire's contact patch has been decreased.

http://www.tirerack.com/tires/tirete...e.jsp?techid=3

I don't see what a 35 year old car has to do with a new ES. Tires constructions are not the same from 35 years ago.

gemigniani

No, it means the weight loading on the center tread is reduced slightly. There are no safety problems running 29 PSI except that wildly aggressive drivers will notice they cannot corner quite as fast . A benefit of 29 PSI is that not only the human body will suffer less wear and tear, but also the car's suspension.

In the late 1970's when tire makers had recommended inflation pressures of 28-30 PSI Toyota owners manuals recommended 22-24. So my point is a wide range of pressures are safe. 29 PSI ES350 tire pressures are less safe only for aggressive drivers who are not driving safely to begin with.

SW17LS

And again...I've been running 31 on my GS with 18" wheels where 33 is also recommended and I have no increased wear on the outer edges after 15k miles.

Joeb427

iTrader: (1)

I think over 70% of vehicle are on the road with under inflated tires of 2 PSI and more.Especially in winter cold.
I haven't been reading of blowouts causing accidents.
2 pounds less isn't a problem.

pmarder

While I generally love my new 2014 ES, I must admit to being very disappointed with the firm ride. Coming from a 2005 ES330 (which I adored), I had grown to being used to a car with a comfortable and compliant ride. Instead, I find my new ES to transmit every bump and at times be almost jarring. The car originally was fitted with Bridgestone tires which I had swapped out for the Michelins. Those tires appeared to be over inflated at 38 psi when I received the car at which point the dealer reluctantly agreed to lower the pressure to 35. I want to lower the psi even more in order to improve the ride but I am confused when to do so. By way of example, this morning it was in the high 40's and when I started my car, the tire pressure system showed my front tires to be 33 while the rears where 34. After driving the car for half an hour and reaching my destination, all four tires read 36 psi. So the question is, do I want the tires to read 33 psi after being warmed up or 33 psi when I start (which would mean that I should leave them be)? Thanks for the help.