Tire Psi Settings

[nc211]

I'm on the hunt after a funny vibration. I seem to have this wierd wobble in my car, and I think it's the tires. I also have what feels like a wheel hop from the back when the car is cold and i'm going slow, like under 25mph.. I've got the Mich. Energy tires on the car and have the psi set at 32. I've gone down to 29 before, smoothes out bumps, but makes steering heavy. I've also bumped them up to 38 on highway trips trying to smooth out the ride. That helps a bit, but makes the road seem harsh. So, what are your psi setting? Blake, I think we've got the same type of tires, I'm curious what yours are set at?

Thanks

[lexguy2000]

I'm on the hunt after a funny vibration. I seem to have this wierd wobble in my car, and I think it's the tires. I also have what feels like a wheel hop from the back when the car is cold and i'm going slow, like under 25mph.. I've got the Mich. Energy tires on the car and have the psi set at 32. I've gone down to 29 before, smoothes out bumps, but makes steering heavy. I've also bumped them up to 38 on highway trips trying to smooth out the ride. That helps a bit, but makes the road seem harsh. So, what are your psi setting? Blake, I think we've got the same type of tires, I'm curious what yours are set at?

Thanks 

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If the rims are not bent, it sounds like at least one tire has a separation. This occurs when one of the steel belts separate out of alignment from the rest. I run 29 PSI do to the fact that the car travels on a lot of brick roads. Dunlops on a 2000 LS400.

[1990LS400]

I also run Dunlops (SP5000) at 29 psi on a 2000 LS400. Keeping the pressure to the minimum smooths the ride on potholed roles in the central U.S.

[dcfish]

I also run Dunlops (SP5000) at 29 psi on a 2000 LS400.  Keeping the pressure to the minimum smooths the ride on potholed roles in the central U.S.

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31 w/Michellin XGT V4's on my gs300 and 32 on my es300 w/ Michellin mx's.

[nc211]

Is there a simple test any tire place can do to see if the rims are or are not bent? It is possible, since she's 10 years old. She's seen a lot of potholes I'm sure. But if the rims aren't bent, what in the world would cause the steel belt to seperate? A pothole hit as well? Can a tire place spot which one it is, or which "ones" :cries: they are? I'm coming to the conclusion that this vibration wobble thing I've got is tire/wheel related and not suspension/rotor related, since I've basically had it for a long time, even before I replaced all the control arms and struts.

[lexguy2000]

Is there a simple test any tire place can do to see if the rims are or are not bent? It is possible, since she's 10 years old. She's seen a lot of potholes I'm sure. But if the rims aren't bent, what in the world would cause the steel belt to seperate? A pothole hit as well? Can a tire place spot which one it is, or which "ones" :cries:  they are? I'm coming to the conclusion that this vibration wobble thing I've got is tire/wheel related and not suspension/rotor related, since I've basically had it for a long time, even before I replaced all the control arms and struts.

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The wheels could be put on a tire balancing machine and spun. You could visually see any major variation if you focused on one side of the rim. Tire separations are more common than most people know. The abnormality it creates when the separation occurs can produce a rhythmic low speed shake. Some cases the separation will cause the car to "pull" to one side. Using your hands you can rub the tread surfaces of the tires all the way around to look for a "bulge" or "bump". A word of caution: If the separation is severe enough the stell belt can be exposed causing you to cut your hands. What speed(s) is the wobble occurring?

[nc211]

It's usually from 10-40 mph is when I really notice it the most, especially when the tires are "cold" from sitting for a long period of time. I've always noticed some type of shake at 40mph range. Is it something that a normal tire balancing service by the dealership should have easily seen at the time? The reason I ask is because they've been balanced several times at the dealership and I've never been told they are bad. But it sure sounds like that's the problem to me. Those symptoms you described are what I'm feeling.

[nc211]

in addition: when the tires are "cold", it feels like a hop. When they're warm, it feels like a left to right wobble.

[lexguy2000]

It's usually from 10-40 mph is when I really notice it the most, especially when the tires are "cold" from sitting for a long period of time. I've always noticed some type of shake at 40mph range. Is it something that a normal tire balancing service by the dealership should have easily seen at the time? The reason I ask is because they've been balanced several times at the dealership and I've never been told they are bad. But it sure sounds like that's the problem to me. Those symptoms you described are what I'm feeling.

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First I would try inspecting the tires visually and with my hands. It would be very easy to do if the car was on a lift and you could address things form underneath. High performance tires can develop flat spots if the tires sit for a long time and the rubber compound is soft enough. Once the tires heat up things will improve. Also I would find a flat level section of road. Stop the car and then let your foot off the brake and let the car roll. I think tire technicians should be perceptive as to the condition of the tires they are trying to balance. It may be worth it to appropriate a half an hour to an hour's worth of diagnostic time to know where you stand.

[nc211]

I don't remember seeing anything wrong with the tires when I had them off when I did the suspension stuff, but I didn't look for anything either. I'll do the slow roll test tonight in the office parking lot. I remember on my first car back in 89 "1987 VW Golf GT", it had bent rims from when the previous owner had it shipped back from overseas "military" and they dropped it. Feels like the same issue. Funny how memory works....Can't remember last Friday night, but can remember a wobble 16 years ago. Must be those beer cheerin' dudes

[blake918]

Michelin MXV4+ @ 30psi...roughly 45k-50k miles on the tires. Sometimes I like them at 40psi to firm things up (especially on long trips or when I travel outside LA since everyone's roads are smoother than ours.).

[Lexls]

32psi for me.

[VMF]

really depends on the tires but avg is 32

i have michelin pilot sport as and i keep them at 32

[baul79racer]

'91 LS 400 with Yokomama's AVS dB decibel S2 with 32's PSI running on 24k at this time. I really enjoy it.

[VBdenny]

Radial tires all wobble at slow speeds because of the radial belts. Some are worse then others though. I use about 35psi in mine and it seems to work pretty good.

[LScott400]

For tire vibration diagnosis there is a great piece of equipment used in many shops. Rather than go into all the technical aspects I recommend you check out this Link. I install and service these machines and personally have experienced great results on my own vehicles. You may notice that there is a tab at the top of the page that will allow you to find shops in your area that have this piece of equipment.

I recently purchased a 94 LS400 and used this machine to mount a new set of Falken Ziex 512's (great price and great ride) and it rides silky smooth.

[cary1952]

i use 32psi.

[VBdenny]

Scott... What is that giant tube coming out of the middle of the back of the car in your picture?

[LScott400]

First car ever made with a JET turbine! Now all it needs is a 70 ft. wing ........... :whistles:

[SKperformance]

I have mine set at 42 with michelin energy's