Once Again Tire Pressure Vs. Vibration

[93LSOwner]

I have read about 3-4 posts about tire pressure and how they effect the Lexus.

This might be an outdated post, but those 3-4 posts are 6-8months old and I don't know how I can related my car to them.

Ok guys here is the scopege:

First of all 1993 LS400 146,000 miles. Alignment and tire rotation done last month, have about 300 miles after the Alignment and tire rotation.

I just went out to visit the Lex. In her crib “garage” to copy the information off the glove box and the tires.

Glove box info:

Cold tire inflation pressure:

1. Load 4 occupants: Front_ 30psi Rear_ 30psi

2. Load up to vehicle capacity weight: Front_ 32psi Rear_ 32psi

Info. from the siding of the Tires:

Brand name: Good Year Eagle T/R P225/60R16 (all four)

Pressure: 44psi Max

____________________________________________________________________

“Higher pressures give a harsher ride, but it's safer, the tires last longer, and you get better mileage. Most new tires all can take 35 PSI or more.” Quote from a 6 month old topic, where some people agreed with it.

When the car goes over or at 60mph it vibrates and the vibration increases with the speed. Vibrates when the gas is applied and without applying it, so, it’s not the engine mounts or any of that business.

All four tries have 35psi“I believe,” done by a local mechanic when the alignment and rotation was done about 300 miles ago. He also mentioned that the front tires are a little worn out.

Alignment which was done 300 miles ago, now the steering wheel is not perfectly centered. “Come on now not after only 300miles”

Now what should the tire pressure be to give a more smother ride. The car is driven 20miles a day in weekdays on a state highway doing 55-60mph. Sleeps all weekend long in the garage 0 miles.

And are all those posts about, high pressure gives harsher ride but better mileage and so forth, are correct or not.

Thanks

[jbarhorst2]

Higher pressure will give a slightly harsher ride. Conversely, lower pressure will give a softer ride. That is true. The tire pressure should not cause the vibration. Sounds like the shop did not properly balance the tires, or a wheel weight has fallen off. Either way, that should not have happened so soon. Did they do a dynamic or a static balance? Dynamic (in my limited experience) tends to give a slightly better result. My tires have 48,000 miles on them and still are in balance from when they were installed. Also, your alignment should not be off. It is possible that they did not tighten everything properly and it is gradually moving. How well do you trust the shop that did the work? Even if you trust them, they could have had an off day.

I would take it back to them and ask them to fix it. If they say "tough luck" then it is either time to get more demanding or find another shop to do your work.

[jbsmithsa]

I also want to know which tire pressure to use. The one that Lexus recommends or the one the tire manufacturer recommends.

[JPI]

I also want to know which tire pressure to use. The one that Lexus recommends or the one the tire manufacturer recommends.

32 psi(pound per square inch).

JPI

[UCF3]

You should use what the Manufacturer suggests. I use 30psi, since I don't have a full load. Otherwise 32psi would be good for the car.

How is your alignment? Is the steering wheel still tilted?

BTW: whoever wrote the higher the pressure, the better the ride, is either retarded, or needs to be put away. Trust your owners manual and references cards.

[98 LS]

I've played around with the pressure both up and down and have found that the "Recommended" pressure of 29PSI cold is the best all-around for my tastes.

It gave me 27 to 28 MPG on a 1400 mile road trip down to the "Big Easy" and "Mardi Gras" festivities last week.

[jzz30]

any suspension wor done on the car?

[93LSOwner]

I have 35psi all around. So, I should use 32psi.

I want a good soft ride and the same MPG as I am now at 35psi. Won't a harsher ride damage the suspension and its part.

The www.fueleconomy.gov and Lexus say that these 90-94 LS400's get 18MPG city and 21MPG hwy, since they recommed 30-32psi won't the test of MPG be done on 30-32psi.

Conclusion: I get 20MPG hwy on 35psi. Reducing to 32psi will reduce the MPG to about 16MPG hwy, correct me if I am wrong.

[jbarhorst2]

Lower pressure will give you slightly lower fuel economy. I have had good luck over the years with fuel economy and tire life by running a higher pressure. I personally run about 38 psi in my SC300 and RX300. Both tires are rated for 44 psi maximum cold. Of course, the manufacturer rated pressure is lower (30-32). You do lose lateral grip when running a higher pressure (the tires don't "give" as much), but I never drive my vehicles at the limit anyway. I notice a significant difference in ride quality at the higher pressure, but it certainly is not objectionable.

[jbsmithsa]

You should use what the Manufacturer suggests. I use 30psi, since I don't have a full load. Otherwise 32psi would be good for the car.

How is your alignment? Is the steering wheel still tilted?

BTW: whoever wrote the higher the pressure, the better the ride, is either retarded, or needs to be put away. Trust your owners manual and references cards.

Which manufacturer? The tire manufacturer or the car manufacturer? I've been using 32psi and it seems to work fine but I've always been curious about which one is the best since they recommend different pressures.

[UCF3]

You should use what the Manufacturer suggests.  I use 30psi, since I don't have a full load.  Otherwise 32psi would be good for the car.

How is your alignment?  Is the steering wheel still tilted?

BTW: whoever wrote the higher the pressure, the better the ride, is either retarded, or needs to be put away.  Trust your owners manual and references cards.

Which manufacturer? The tire manufacturer or the car manufacturer? I've been using 32psi and it seems to work fine but I've always been curious about which one is the best since they recommend different pressures.

The best pressure is the Auto-manufacturer. it's used to test the vehicle, not the tire.

[tansupplyman]

If the car sits all w/e, you may get that 'nylon' thump for several miles[regardless if it is NOT nylon and whether it is one brand or another]. More true in winter since it takes longer to warm up. I have it with Michelin X-one's and I get mad every time I feel it !!! Will trade up to better tires-V- when these wear out--which I don't ever think they will--530 wear rating

Run 32#; also use the visible pressure valve caps--good if you have slow rim leaks[$10. at Advance or AutoZone]

[VBdenny]

Tan, what are the valve pressure caps you are talking about? I guess I have missed them completely.

[tansupplyman]

These are the exact ones sold at Adv and Autoz. and same price. Pressure levels are from 32-36#. I have 4 sets of them----one glance will tell you if a tire is low. Sometimes with radials it is hard to tell. :P

http://shop.store.yahoo.com/rodi/vicv700series.html

[tansupplyman]

occasionally,an exact pressure valve cap(request an exact pressure) is available at the bottom of this page--------scroll all the way down. Listed as 'Monitor pressure valve cap'