"Inflation pressure does not affect grip": Autospeed article.

[shovel]

Originally Posted by dcb

nooo... it isn't cuz Explorers are topheavy and should require special licensing as well as propery linflated tires, noooo. LOL!

Wha?

early generation explorers, along with early gen landcruisers, early broncos, troopers, samurai, and all the other "OH MY GOD IT FLIPS OVER ALL THE TIME!!! OH NOOOOOOOOOOO" 4x4's out there handle differently than family sedans for a reason... they need ground clearance and suspension flexibility in order to do their job, which is travel across inclement terrain. at their time of introduction I doubt the manufacturers expected them to be daily drivers for people living in san diego.

instead of putting the blame on ignorant drivers who think they can treat a 4x4 like a sports car (you wouldn't drive a corvette on the rubicon trail, would you?), society decided to blame the vehicles. so now the manufacturers have had to produce neutered, heavy and inefficient wagon/vans named after the previously useful 4x4's, with the inefficient vestiges of their ancestors but few if any of the advantages that made them useful to their original audience in the first place.

i think we should go back to making capable 4x4 utility vehicles, install sophisticated motion sensors in them to determine if you are driving aggressively or with disregard for the type of vehicle they're in - if so, the electronics should coast the vehicle to a stop and then begin bludgeoning the driver with a stick while berating them for being a moron.

mankind can never develop as long as we keep reducing everything to the lowest common denominator and keep catering to the whims of anyone who decides they're "offended" by something.

[Christ]

Originally Posted by CapriRacer

Headline: Rollover fear tied to tire warning

A Ford document shows the company urged low tire pressures to keep Explorers stable.

Worldandnation: Rollover fear tied to tire warning

So we're talking about one tire mounted on one vehicle that has already been defined as inappropriate for said vehicle...

I'd be willing to bet that the largest cross section of rollovers that occurred, in the 10s, out of the 1000s that were sold, were only coincidentally linked to higher tire pressures because of FoMoCo's test reports.

Lets see some data that proves that higher tire pressure can lead to a rollover condition, not something that shows that one vehicle with a specific tire functions this way.

[orange4boy]

Could it also be that, in the case of the Exploder, the increased pressure also increased traction which would made rollover more likely in fast turns/manouvering?

Since my topic was passenger tires and passenger cars have a high resistance to rollover, I'm happy to with withdraw that first item. but let's leave it there for now, ponderous as it is.

Updated list of max sidewall Pros and cons.

Upsides of max sidewall:

1) Reduced risk of rollover resulting from loss of control from heat related tire failure.
2) Reduced failure from overheating
3) Slightly reduced stopping distances (may have to do with increased traction)
4) Reduction in hydroplaning (onset of hydroplaning happens at a higher speed)
5) Reduces slipping in snow* (depending on conditions, sometimes lower pressure is better)
6) reduces body lean in cornering, improves steering feedback (subjective)
7) Reduces fuel consumption
8) Steering effort
Downsides to max sidewall:

1) slightly harsher ride quality.
2) may increase rollover tendency in already rollover prone SUVs
3) Harder on suspension components in rough road conditions

Will add / edit this later.

[jamesqf]

Originally Posted by shovel

...4x4's out there handle differently than family sedans for a reason... they need ground clearance and suspension flexibility in order to do their job, which is travel across inclement terrain

I have to wonder about that, though. If you look underneath most of these, you'll see that they have solid rear axles, which means that any increased ground clearance is purely a function of the larger tires. Jacking up the body just gives the illusion of more ground clearance while raising the center of gravity.

This is especially true of aftermarket lift kits, which elevate the body (often to absurd heights) while leaving the lowest point unchanged.

[gascort]

An interesting debate, everyone. Like most, I agree with the main concepts here (I teach Physics) that increased Surface Area does not affect frictional force; increasing SA decreases pressure, reducing the frequency of microwelds.
We do laboratory tests in my class (not with tires, but with a variety of materials, including rubber) and the average results over many trials and groups indicates no change in friction by changing the SA by doubling or even quadrupling. Changing the normal force (weight), on the other hand......
On an anecdotal note, I have some huge tires (315/35R17), or 31.5cm wide, on my mustang. Just for looks - not for aero or friction for sure. I get all sorts of comments about how it "must hook up good" and I can't take time to correct everyone. It hooks just as well as the stock 245 tires I had. Maybe worse, I think these tires are harder. When it is raining, though, I can get sideways on the freeway if I hit the throttle. Then I wish for skinny tires.

[Christ]

Originally Posted by gascort

An interesting debate, everyone. Like most, I agree with the main concepts here (I teach Physics) that increased Surface Area does not affect frictional force; increasing SA decreases pressure, reducing the frequency of microwelds.
We do laboratory tests in my class (not with tires, but with a variety of materials, including rubber) and the average results over many trials and groups indicates no change in friction by changing the SA by doubling or even quadrupling. Changing the normal force (weight), on the other hand......
On an anecdotal note, I have some huge tires (315/35R17), or 31.5cm wide, on my mustang. Just for looks - not for aero or friction for sure. I get all sorts of comments about how it "must hook up good" and I can't take time to correct everyone. It hooks just as well as the stock 245 tires I had. Maybe worse, I think these tires are harder. When it is raining, though, I can get sideways on the freeway if I hit the throttle. Then I wish for skinny tires.

Reminds me of a guy I saw on RT 270 in MD (off RT 15S) with a big azz diesel (He had TRUCK NUTZ, too. ) Decided to shrug off the speed limit and show his ass and all the black smoke he could muster with his Banks' Six-Shooter setup (Banks' sticker in the rear window)... and totalled the truck at ~80 MPH because when he throttled it, the turbo spooled, causing the tires to spin on the wet ground, slinging the truck sideways in front of the person he was obviously showing off to, and sliding into the median (he was passing on the right) strip, basically totalling his truck. What a fool. He's lucky he didn't roll it, the stupid ass. I didn't bother stopping to see if he needed help, I just kept on my way. When I came back through, the truck was gone, and there were several sets of tire tracks in the median. I can only assume his "mo-powa" buddies came and pulled him out and took it home so he could lock it in the garage.l

[orange4boy]

Instant karma!

[Christ]

Yeah, I love it when it happens immediately.

I didn't stop because of my beliefs. If someone other than the Darwin contestant had been involved, I would have stopped. Thankfully, he twisted in front of the other person so quickly that they had no need to react in order to miss him. It was a perfect example of harmonic fluidity in motion.

[orange4boy]

Harmonic Stupidity in Motion II,
The Sequel.
Starring Buddy Whatsisname and an cast of tens.


I saw an almost identical accident with a junker Monte Carlo who was in a passing contest with another car at about 50 mph. After they passed us, he pulled up on the right of the newer car, floored it and swerved towards it, trying to scare the driver. He over corrected and ended up in a swerve oscillation, a spin and a 20 mph smack into the median. Luckily he missed everyone else by inches. His car would't start so he had to push it off the road in front of all the stopped traffic. Total instant Karma.

I laughed, I cried, I only wish I had some popcorn and a slow motion replay button.

[Christ]

Originally Posted by orange4boy

What was going on in his brain.


I saw an almost identical accident with a junker Monte Carlo who was in a pissing contest with another car at about 50 mph. After they passed us, he pulled up on the Vtak knob, floored it and swerved towards the obvious opponent in the next lane, failing at the most basic of ricer maneuvers. To salvage his dignity, he attempted to show off by fish-tailing intentionally, like he saw on a video game. He over corrected and ended up in a swerve oscillation, a spin and a 20 mph smack into the median. Luckily he missed everyone else by inches, which further added up the "cool" points that he would later receive in his own little world. His car would have started, but he felt the urge to wave at those he had just offended, so he had to push it off the road in front of all the stopped traffic. Total instant ricer win.

[/epicFail]

Changes in bold.