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Rx350 Tire Pressure


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#1 pauljcl

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Posted 24 February 2009 - 12:54 AM

I took delivery of a new RX350 about three weeks ago. It has the 18" wheels with the Michelin Energy 235/55 tires, which Lexus recommends driving at 30psi, whether fast, fully loaded, or not (the 17" wheels/tires seem to be recommended 30psi to 33psi). I tend to like tires a little harder and more responsive than the manufacturer generally recommends, and I have tried several pressures... and find that 32 psi front and back seems to give me the best combination of comfort (no 'hitting' on bumps or holes) and smoothness and 'feel'. [I tried 34psi and 30 psi - tires are rated 35psi max]. Does anyone have an opinion on that, or on different front/rear pressures?

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#2 RX in NC

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Posted 24 February 2009 - 09:34 AM

I've run my wife's 2004 RX330 AWD's Bridgestone Alenza 235/55/18 tires at 36 psi year-round since the tires were mounted in mid-February 2007. The tires now have more than 46,000 miles on them and have performed flawlessly. 30 psi will give you a cushy ride but wear your tires out prematurely while cutting into your mpg. 32 to 34 psi is preferable to 30 psi, no question about it, but if you want to extend your treadlife and gas mileage, bump them up to 35 psi and try it for awhile. You can always reduce your pressures if you find the ride a bit too harsh for your liking....

#3 pauljcl

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Posted 24 February 2009 - 09:45 AM

I've run my wife's 2004 RX330 AWD's Bridgestone Alenza 235/55/18 tires at 36 psi year-round since the tires were mounted in mid-February 2007. The tires now have more than 46,000 miles on them and have performed flawlessly. 30 psi will give you a cushy ride but wear your tires out prematurely while cutting into your mpg. 32 to 34 psi is preferable to 30 psi, no question about it, but if you want to extend your treadlife and gas mileage, bump them up to 35 psi and try it for awhile. You can always reduce your pressures if you find the ride a bit too harsh for your liking....

Tks. for your comment. Mine's an AWD, too. I had found the Michelins' ride marginally too harsh at 34psi - it may well be that Bridgestones have a smoother ride at the same psi than the Michelins do. I assume you run the same psi front and rear? I was curious to see whether anyone ran different pressures front and rear. [The MB350ML runs something like 32psi front and 32 or 34 to 37 rear, depending on load - of course, it a heavier vehicle with a different tire size].

#4 rx350guy

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Posted 07 March 2009 - 10:33 AM

Of course all this also depends on what the low pressure warning sensors are set at as well. I believe my dealer rep told me that mine were set at 33 psi.

#5 pauljcl

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Posted 07 March 2009 - 01:38 PM

Of course all this also depends on what the low pressure warning sensors are set at as well. I believe my dealer rep told me that mine were set at 33 psi.

Actually, reading through the Manual, it would seem that you can re-set the Tire Pressure Warning at (or maybe it triggers slightly below) the level at which you normally set your tires: once you have set your tires to the pressure you wish, there is a simple procedure which sets the 'water mark' at that level. When I got my new RX350, the Warning set off at 25psi - and I left it there despite using 32psi all around. [I check my tire pressures often enough; and if there is a 'flat', 25 psi is good warning. I don't want the Warning to go off unless really needed]. There is no indication in the Manual of how much 'leeway' they allow from the set pressure.

#6 SmilingBoognish

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Posted 09 March 2009 - 01:07 PM

I've been setting ours at 33, and they're usually down to about 32 by the time I do my monthly cold tire pressure check.

WRT the tire pressure sensors, they are utterly worthless, imho. Ours always go off when driving in the mountains. I'm guessing the spare gets cold and it sets off the idiot light. There is a very easy procedure to reset the idiot light in the owner's manual. It's far easier to do that than it is to actually check all the tire pressures (spare included) to make certain there isn't really a problem.

edit: pauljcl may be on to something. Before I drive to the mountains again, I'll lower all 5 tire pressures to 25 and then reset the sensor. Then I'll put the appropriate amount of air in the tires. I wish everyone would check their tires so we wouldn't have to pay extra for these nanny systems...but I understand that would be asking far too much.

#7 pauljcl

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Posted 09 March 2009 - 11:44 PM

I've been setting ours at 33, and they're usually down to about 32 by the time I do my monthly cold tire pressure check.

WRT the tire pressure sensors, they are utterly worthless, imho. Ours always go off when driving in the mountains. I'm guessing the spare gets cold and it sets off the idiot light. There is a very easy procedure to reset the idiot light in the owner's manual. It's far easier to do that than it is to actually check all the tire pressures (spare included) to make certain there isn't really a problem.

edit: pauljcl may be on to something. Before I drive to the mountains again, I'll lower all 5 tire pressures to 25 and then reset the sensor. Then I'll put the appropriate amount of air in the tires. I wish everyone would check their tires so we wouldn't have to pay extra for these nanny systems...but I understand that would be asking far too much.

I also set my spare at 3-4 psi above the pressure I run my tires at. It's a lot easier to let out pressure if needed than to add (in the event you need to use the spare), and it allows less frequent checking of the spare - the RX350's spare tire location is a pain..

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