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914lps

How Full Of It Are You?

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Lexus states thet the tires on my 91 LS 400 should be 30 lbs both fron and rear. I have goodyear assurance tires on the car now ( I like them) they are rated at 44 lbs max inflation. That is a 14 lbs diferance.

I know 44 lbs is the rated max. amount. Not a recomendation on what to inflate to.

I also know that Lexus recomends 30 lbs to get a better ride, without regard for MPG or tire life.

I have been running them at 40 LBS. The ride seems a little more "sporty" and the tires handle better ( I know, as more LBS in tires stiffen the side walls, so you get better handaling) I also picked up 1 MPG over running at 30 LBS and my tires will last longer. I mainly run at the 40 LBS to get the tire life and MPG.

What do you folks run your tires at and why?

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I tried all sorts of tire pressures early in my 13 1/2 year ownership of a 90 LS400 but settled on the recommended 30 psi cold inflation. I went as high as 44 psi and tried running different pressures in the front and back tires. The recommended 30 psi seemed to give the best comfort and the most predictable handling. The higher pressures seemed to cause more abrupt and less predictable breakaway on sweeping curves and I didn't want to put my baby in the ditch. My wife seemed to notice - and not in a happy way - when I had the pressures set even a little higher that recommended.

I run the recommended (29 psi) in my 2000 LS400 and in our Camry and adjust the pressures frequently as the ambient temperature changes. I set them to 33 psi yesterday in a 50 degree F. garage since I will be heading north towards 10 degree F. temperatures. One needs to add or subtract one psi for each 10 degrees of temperature change.

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I run my tires at manufactures spec, but I also currently use the manufactures spec tires on the car (sizes and speed rating).

The pressure recommendation that Lexus gives you is not for ride comfort specifically, it is the level which you should inflate the manufacturers spec tires to in order to have the proper amount of tire flex and ground contact with those wheels based upon the weight of the car at the 4 tires. You will read in your manual that it recommends higher pressure if you are towing in the back wheels... This is so your rear wheels stay the same shape as they normally are when they are not towing.

Keeping your tires at the desired shape will require different pressures as you plus size your wheels or change the load on your tires.

The amount of "footprint", or ground contact your tires have will influence the ride of your car. Tires are meant to rid with a certain amount of sidewall flex making the weight that each wheel bears to be spread out evenly over the cars footprint. A "low pressure" condition will create a larger footprint as the tire is "flatter" on the ground, and will therefore give more grip, but will reduce handling responce as the strength of the sidewall is lowered in this condition. It will also allow the tire to wear unevenly and lower than expected treadlife, as well as lower fuel economy due to greater resistance to forward motion.

A "high pressure" situation will reduce the size of the tires footprint as the tire is now rounder. Your handling will be more stiff and responsive. Your ride will bounce a little more especially in a pothole type of situation, and the tire will wear unevenly and lower the treadlife of your tires. Having a smaller footprint will also increase your stopping distance, which will definitely be the most unsafe thing you could do to your vehicle, as braking is the difference between life and death. Your fuel economy will increase due to having less resistance for the car to move forward.

Those are the dangers to having over and underinflated tires, but like I said before, every tire is different and the pressure on your car-info badge is the pressure for the tires on the car info badge. Changing the tires in any way will change the optimum pressure that the tires should run at.

Story: A colleague of mine had a mid-nineties ford F series truck. He doesn't care about braking or handling, but only saving money. He inflates his tires to 50 PSI (goodyear wranglers I believe). I am not sure what the reccomended inflation is for his truck, but he does overinflate. He rides alot of dirt roads and finds his tires do not last long regardless of inflation, but he saves money when they are overinflated. I am not sure how much of a savings it was, but overinflating the tires ended up saving him alot of money in the long haul because the fuel savings were high enough to negate the costs of replacing tires a bit earlier........This worked for him, but please keep in mind the degradation in your rbaking if you do overinflate, especially if you drive alot in "pedestrian rich" areas or at high speeds.

Merry Christmas!

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i run all 3 of my cars at 32 psi. it also depends on what kind of tires you have on the car. on the 96 i have michelin pilot sport 225/60/16 that are Z rated, even at the 32 psi they give me pretty good handling. on the civic i got pirelli p zero nero 215/45/17 and the 04 ls i have some not very good kumho H rated tires. the softer tires you get the more life u gonna get out of them but the handling is going to be worse. i got 96 with t rated tires, it was like driving on the baloons, the whole car was shaking and swerving every time i would do a hard turn or change the lane at high speed. after z rated tires were installed its like a completely different car now:) so its hard to say whats the best pressure since the tire size, tire rating and the state of your suspension play a big role in the whole driving experience. my civic with 1 inch drop and 17 inch rimz with z rated tires is pretty stiff even with 30 psi but it keep it up to 32 to protect rimz from ny roads:)

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I have 225/60R-15 94V BFG Traction T/A V tires on my 90. They are on the factory rims. I keep 33lbs in the tires cold. Lower inflations do somewhat seem to help the handling and ride but they wear out faster and return poorer fuel economy. On my ES330 I have Yokohama Avid V4's at 225/60R-16 94V. I keep 34lbs psi cold in them.

The LS gets right around 25mpg and the ES gets 30mpg. This is driving on Interstates between 55 and 85.

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