Vicious.

I figured I'd be nice and make 1 thread out of this.

First off, I just bought a decent tire guage and found out that the guy that had the car before me had been running the tires at about 30 psi or so. They're Eagle RSAs with a max rating of 44 psi. I'm going to try running them at 40. Anyone see problems with that?

And I'm having the common problem of clunking from the rear when I hit bumps in the road. It was there when I bought the car and I was told that it was a rear swaybar bushing. I squeezed under the car to take a look and I don't see anything wrong with either of them. They weren't cracked or torn or missing or anything. What exactly does a bad bushing look like? I also tried to look for other signs of the noise, but my shocks look all right from underneath, the swaybar endlinks look fine, and I'm not entirely sure where the torque arm bushing is, or I would have checked that too. Any suggestions, or better yet, pictures of things that are known to be broken?

JEB Garner

Just because you tires state they can handle 44 pounds of pressure does not mean that you should run that kind of tire pressure. With that much pressure you are creating a number of problems. First: that much air pressure is unsafe because as the tires heat up on the road and the air pressure is going to increase. That 40 pounds becomes no telling what. Possible blowout. Second: your ride will be like a wagon. Third: you will shake the car to pieces. Now,that important Forth: Your handling will be gone. Hard tires do not grip the road very well. Not only will hard tires (High air pressure tires) not grip the road in corning, they will not stop very well either, again due to the high air pressure. Why do you think that the NASCAR crewchiefs start their drivers out with each tire change with as little as 15 pounds of air pressure in their tires. YES, you want and need a bit more air pressure than that in your street car tires. Probably some where in the 26 to 30 pound range. Tire pressure is a very important issue. One that many driver over looks in car care. For your safty and for the safty of all the others that you may meet on the highway, PLEASE DO NOT RUN 40 POUNDS OF AIR IN YOUR TIRES!!!

Camaro_SS

iTrader: (1)

Not bad, Jeb, but don't go all Ralph Nader on the dude.
The rated max pressure of the tire (44 in your case) is the maximum pressure recommended at cold and with the car at max load weight. Today's tire compounds can safely handle consistent overpressures of up to 15-20lbs. Running that amount of air pressure will "harden" your overall ride characteristics. However, it will also stiffen your tire up some, so handling will, depending on your tire's compound (wear rating of 220 or less is considered sticky) improve some. When roadracing, I like to up my normal tire pressures 5-7lbs, depending on weather, track conditions, tire compound, etc. I run Kuhmo712's on my T/A, with 35lbs. cold pressure. Those tires have a 300 wear rating, and max. pressure of 44lbs cold.
So, is 40lbs cold too much? Depends. For short around-town trips, I'd say it depends on what kind of ride quality you prefer. For highway trips, you'll experience ride harshness and faster wear.
I won't even comment on your NASCAR comparison, but suffice it to say you are a little off-base on that one.
Hope we helped.

WhiteRhino

iTrader: (6)

Do you have any facts to back this up? You should do some research before giving out what seems to be 5th hand info. Our cars aren't prostock, and don't see the temps thats created in Nascar or auto-x or any other form of racing. Nor do they have racing tires on them!

Manufacture's run lower air pressure to give the car a better ride while still meeting gas mileage requirements.. Check your doors, they say some rediculously low amount as well on most other cars. Running a tire with 40 psi that calls for 44 psi will not cause a single issue. Most tires I know of are rated a cold psi not hot. Also running to low or to high of a pressure ruins the tread life. You also get better gas miliage with the correct pressure, or a higher pressure. The majority of road hazzards come from tires not having enough pressure. They're softer allowing more debri to be picked up. Also you are more likely to have a blowout with an under inflated tire than a tire at the recommended specs. Notice I said the recommended specs not over inflated. Also a softer tire is more likely to blow out if you do strike an object.

You can run a chalk line across the tire tire see how the tire is tracking. Thats a little much, but I did that with my rears. They're 315's on 17x11's so I wanted to make sure they weren't cupping or running on the center of the tire. They're Bfg Kd's and call for 42 psi cold. I run 40 psi in the rear and 42 psi in the front. I guess I better go drop them down to 30 psi so I dont have a blow out and I can gain gain my handling back. No wonder my car is shaking apart

Here's a couple links. Just google tire pressure.

http://www.nhtsa.dot.gov/cars/rules/.../brochure.html
http://www.mad-ducati.com/Articles/TirePressure.html
http://www.edmunds.com/ownership/saf...1/article.html

Camaro_SS

iTrader: (1)

Ouch. And I was trying to be nice about it. But, well said anyway.

01WS6er

iTrader: (2)

I also run the Kumho 712 on my car. I run 37 in the frt and 35 in the rear. I do notice a little rougher ride than compared to 30 all the way around.

As states before all cars are different as per the way you drive your car. I drive my car about once a month and then it is pretty aggressive. I run more in the frt to try to cut down on the tire roll on corning . The tires have about 5000 miles on them are are wearing straight accross and are not cupping. My suggestion is to run the tire press of choise and see how you lilke the ride, if to rough than lower the press down adn try that. just my .02

WhiteRhino

iTrader: (6)

It's not that I wasn't trying to be nice. Sometimes people, not that they give bad advice, just don't give the right advice. I'm guilty as well from time to time. Tires are a very important maintainence item. It's best to just research it than to give out info that seems all hearsay, like something someone was told through the grapevine. I mean no direspect to JEB Garner and am sure that he hopefully loves this board as much as the rest of us.

I see you are fairly new to posting on the board as well. So welcome to the board as well to Jeb, there's plenty of great info if you use the resources. It took me years on the board before I started posting. I just did alot of reading. Hence I'm not a postwhore, but I'm working on it!

JEB Garner

At least my commits got you guys busy posting. Now Vicious has some idea as to what to do about air pressure.

Camaro_SS

iTrader: (1)

Thanks, but I've been a member for almost four years now. Note sig. Had to renew the membership after a hiatus from the internet, and civilization, in 2002-2003.

BigDaddyZ28

I run my RSA's at 32psi. No problems so far for me and the car rides and handles well at 32. FWIW, either the door sticker or the owners manual (I can't remember which) says to air them up to 40 psi for 'extended periods of high speed driving'. I am pretty sure it specified that '100+ MPH driving' should be set at 40.

40 psi is NOT going to hurt anything on your car or your tires.

Camaro_SS

iTrader: (1)

...and back on topic; the torque arm bushing is bolted onto the transmission, driver's side, next to the shift lever housing area. Rarely does that present any problems, though. You say the noise is only present when going over bumps? I would check your rear upper spring brackets for looseness. the rear springs can rotate slightly, so that the end of the coil at the top comes away from the bracket stop. When compressed (going over a bump, say), the spring will move, and slap the bracket. At least it does on my wife's T/A. But it's hers, so I haven't done anything with it.

Vicious.

Yes, thank you all very much. I'll play around with the pressure until I find something I like. I was just always told to do the max pressure or a couple pounds under.

And the clunking almost sounds like a problem that I had with an old Taurus with a busted shock tower. Any time it hits any change in the road, it thunks. But I tried pushing down on the back end of the car and beating on everything I saw underneath it, but I could not recreate the noise. I'll go check out the springs if I can manage to squeeze under there again.

Thanks for the help.