Rough ride with my new high performance tires (tire pressure?)

You ought to be able to get an idea of what each corner's actual weight is from the mfgr's curb weight specs and also the published weight distribution. Armed with this info I'd call your tire dealer or Kumho (assuming they have a 1-800 info number) and ask what the minimum pressure is that you should be running for that weight. They ought to be able to give you this info. Judging from the size, I'm guessing this is a rather large vehicle, so you probably will have to deal with a fairly high pressure and rough ride... kinda goes with the territory when you run low profile tires.

nate

You can probably let out all the air & still have a harsh ride. No sidewalls = no ride quality. Shoulda done some research before spending all that $$ just so ya can irritate your hemmeroids. good luck.

Take off those rubber-bands stretched around oversized bling-bling rims, and put some real tires on. Or learn to live with lousy ride and handling in return for the look you want.

Sorry, but I just don't get this whole "looks take precendence over function" thing going on with godawful big rims these days.

Running tires underinflated on an SUV is a known safety hazard, as well as hard on your tires. It is a common cause of premature tire failure; and many SUVs have such a small margin of stability that a blowout may cause sudden loss of control or rollover. Best case, you void your warranty. Worst case: Ford Exploder. Darwin Award.

When you asked for advice on another group, you were warned about the ride due to the small sidewall on 50 series tires, but you insisted that '6"' was plenty of sidewall. Live and learn. Trucks are not sports cars, and the tall tires they generally come with are there for a reason. Trucks and sports cars do have one thing in common, and that is a firm suspension. The sidewall on your tires are your last chance at comfort in either one, and you chose the least comfortable size (short of a 40 series).

In order for your tires to safely carry your vehicle, you will need to make sure your tires have the psi the tire guys put in. Low profile tires are not very forgiving with low preasure, and will easly show your wheels the pavement when you corner without the correct PSI. FYI, any other brand of low profile tire will give you just as rough a ride as your Kumho's. 60 series tires would have given you the best compromise for looks, comfort, and performance.

Or were you hoping to go auto-crossing in your truck?

Approximately 9/30/03 09:42, Christopher Green uttered for posterity:

Oddly enough, running tires overinflated on an SUV is also a known safety hazard and a cause of premature tire failure and a known source of additional handling instability. Even odder, running sticky street performance tires on an SUV even at standard ride height is also a source of unnecessary rollovers.

Checked and there was 46-47 psi in the tires, way too much. I made it

Steve, you made a poor and ultimately incorect assumption. This was a functional upgrade. It took me a while to find 20" rims that weren't chrome (I hate chrome), but in the end I found some nice understated silver painted rims, and some great reinforced tires to complement them. Now the truck is more maneuverable, and as a result, much safer than it was stock.

Steve (and you too, Lawrence) - f*ck off. If you are representative of who hangs out here, you deserve your own company, and no one else's.

Say>

Do you really mean it this time? You're leaving?

DS

An easy way of checking for correct tyre pressure on a non std application is as follows.

Paint an even line about 1" wide across the tyre tread of each tyre with white paint. Doing it between two strips of masking tape makes for a more precise job. Do it adjacent to the tyre valve which makes it easier to find the line again. Let it dry then drive the vehicle gently for a few miles on straight roads. Take corners very slow because you don't want to scrub the paint off. Stop and roll the vehicle forward until you can see each line in turn.

If the paint is wearing away in the centre but not the edges then the pressure is too high. At the edges but not the centre and it's too low. Lots of negative camber will remove the paint off the inside first so you need to look at the centre and outside edges to get an idea of what's happening. If the tracking is out then the tyres will be scrubbing anyway so get that fixed first. Play with the pressures until the paint wears away evenly and you're as close to correct for that vehicle weight as you need. You can adjust by a few psi either side of that to get a better handling balance if necessary. Increasing the front pressures compared to the rears will reduce understeer and vice versa. My own preference is a for a few psi above ideal which helps economy more than it hurts tyre wear and allows for carrying loads without having to readjust the pressures.

Dave Baker - Puma Race Engines

come on is swearing required.

At least you didn't get those dumb-ass shiny rims.

FYI, you're the one that started the name calling. I even gave you a link for a Chevy Avalanche fan club, where are others with your truck, and similar interests, and you were still leading the shit slinging. Humility is not in your nature. Too bad. It could have lead to a more productive discusion.

It's funny how now that you got your tires and you switched groups, you got similar comments but you weren't as nasty. Except of course, for those who browse all the auto groups, and had answered your first post.

Sayonara, s*****ad.

Another idiot rides into the sunset.... hope he doesn't wipe out innocent people when he crashes that thing when he pulls a bead off the rim during a corner.

"Functional uprgrade" my butt. SUVs need real tires. If you want to improve handling, do the RIGHT thing and upgrade stabilizer bars and other suspension components (including mild lowering and appropriate correction to suspension geometry if necessary), don't just put rock-hard poseur tires on it and think its going to be an improvement.

When you're incapable of expressing yourself any other way, then yes it is. :-p

I never 'switched groups'. I posted the same question to two groups at the same time (since it is not nice to cross-post to more than one group). The group with the nice people gave nice replies, and got equally nice responses from me in return. The folks in this group, on the other hand, got exactly what they put out - arrogance and attacks.

Sorry, funguy, but one person made a joke, and you let fly with the insults. And the same people who browse this NG, browse the others, too. It's just pointless to make the same insults in all off them, when one will do. You'll get the same answers, from the same people. And I have seen as much sarcasam in some of the postings in the other group. You just weren't as nasty in return. You could have ignored it here like you did in the other.

And truly, I am sorry to hear about the rough ride from the tires. I know you probably invested a good chunk of change for them. The tires on my car are 195/50 on 16" rims, and they are a rough ride. And that's what came on the car stock. They can be tiring on long drives, but the car is a blast to drive on winding roads.

Good luck. (no rudeness or sarcasm intended)