Tire Pressure

[volksworker]

It may compensate for handling problems but that doesnt keep a tire from overheating at speed...........better handling wont keep someone from losing control when a tire shreds. The 2 cars you mention are 35 and 45 years old as are their tire specs. I have owned both. I should also say that truck tires not fully loaded can be run with less pressure but the 20 percent rule is still close. Nobody driving a Thing with 195 14 or any modern radial pasenger tire of standard design should run less than 28 psi at speed. I mean its sort of ridiculous to think that every possible tire you would put on a Thing should be run at 18lbs......................doesnt it.
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Tom
41 Ford super deluxe convertible
57 MGA coupe
65 Mercedes 230sl Pagoda
67 Porsche 912 Bahama Yellow
67 Olds 442 convertible
70 Ranchero GT
73 Thing original
73 Lancia Fulvia Coupe'

[EverettB]

For reference, some obvious stuff:
1. The stock tire specs. apply only to stock tire sizes.
2. Tire pressures should be set cold, meaning check them at your house before you drive to the gas station and fill them up.

AZ is the king of tire shredding but I think that's more from sun damage? The only time I have had tires come apart is from sidewall cracking due to age and sun. Coincidentally(?) the ones that shredded were the rears at 30 psi, not the fronts set to 20 psi.

The crap all over the roads are big rig retreads from what I have experienced, not passenger radial tires.

The last time I asked the opinion of a tire shop, they told me to use whatever the car stated.

Here's another post regarding this:
http://www.thesamba.com/vw/forum/viewtopic.php?p=2960541#2960541

If you have a big load up front or back, you should definitely increase the tire pressure to compensate.
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[bciesq]

I run 20 up front and 30 in the rear. Stock size passenger tire.

The furthest I've gone in one shot is 600 miles in a day. No problems. The car is daily driven. I don't rotate the tires and there is no sign of uneven wear. Side walls show no sign of cracking or rot.

YMMV.
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'73 Thing -- making 45 mph exciting again.

[volksworker]

The tires you see on the road are victims of internal temperature........not retreads. The large pieces you see are 18 wheeler tires obviously. The external sidewall cracking caused by UV light doesnt have anything to do with the structure of the tire , though it may be a sign of age which is not a good thing. I dont think anyone even does retreads in Phoenix anymore, maybe for large trucks. I used to get them all the time and buy reclaimed motor oil too.....I also used to think that retreads were on the side of the road too [I think thats was my dads answer in 1966] but those pieces arent retreads......again the link directs you to people saying their car drives great or better with low tire pressure............like I said it covers up a host of other problems but that doesnt make it correct. Low tire pressure at speed equals heat build up and delamination. A stock thing cant go fast enough to really cause a problem but over 70 mph temp is everything. My 181 is stroked with a freeway flyer so it matters to me. "It works on my car" is not a sound answer. The wrong answer can be dangerous
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Tom
41 Ford super deluxe convertible
57 MGA coupe
65 Mercedes 230sl Pagoda
67 Porsche 912 Bahama Yellow
67 Olds 442 convertible
70 Ranchero GT
73 Thing original
73 Lancia Fulvia Coupe'

[Al Capulco]

"The wrong answer can be dangerous". Well said. The point I was trying to make was that axle load is a critical factor in determining proper tire pressure. I think everyone would agree that under inflated tires are the most common cause of tire failures. However, over inflating them can be just as dangerous. Most tire companies follow vehicle manufacture recommendations regarding proper tire pressures or use a tire load/inflation table to determine pressure if things have changed.

[Russ Wolfe]

The factory inflation pressures that are recommended, are to give maximum contact patch with the road.
And contact patch ultimately is what steers and STOPS the car.
As for the factory shipping the Thing with innertubes, that is correct. It was a safety thing for off road. So when you hit a rock, you would not deflate the tire. The vehicles also came from the factory with safety rims. Meaning the had a groove in the rim where the bead seated. This too was to help against deflation with side loads. Many aftermarket alloy wheels do not have this safety feature machined it. Any wheel that does not have the safety rim feature should run innertubes.
If I remember correctly, things came with radial tires, so the stickers in the trunk or where ever, are refering to radial tires. It doesnt make a difference if they are p-Metrics or not.
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[vwthingboy]

FYI, http://www.tiresafety.com/maintenance.asp
sponsored by Bridgestone and Firestone says:

Many people ask "what air pressures do you (meaning tire companies) recommend for cars under normal conditions?" The answer is "we recommend what the vehicle manufacturer recommends."

and

What criteria do the car manufacturers use to determine inflation recommendations
* Ride
* Load capacity
* Traction, wear
* Fuel economy/Rolling resistance

The Gubmint website http://www.safercar.gov/ also says

"Remember, the correct pressure for your tire is what the vehicle manufacturer has listed on the placard, NOT what is listed on the tire itself."


**So does the question remain: Is 18psi too underinflated/unsafe for a modern tire?**
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Duffer 2005-2012

[stevehenderson]

"So does the question remain: Is 18psi too underinflated / unsafe for a modern tire?"

If it is not inside the designed rage for that tire the tire manufacturer would say it's unsafe. "Firestone has claimed that they have found no faults in design nor manufacture, and that failures have been caused by Ford's recommended tire pressure being too low."

I imagine VW would say buy a tire the recommended size that can be inflated to there recommended pressures like most new car dealers do. Your driving stile and road conditions certainly could alter whats best for you but may be taking a chance as concerned with safety.

[madster]

So 18lbs front and 29lbs rear?
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1966 BEETLE @ 1973 THING

[SilverThing]

Correct. I have found that anything more than 22psi on the front makes the steering noticeably light, which I take to mean that I am negatively impacting the contact patch.

The last time I had a tire shop replace the tires on the rig, they inflated them to 35 psi all the way round. I didn't even leave the parking lot before I noticed and immediately stopped to air them down. I'm sure they thought I was crazy, but I wasn't about to drive around on over inflated tires and the resulting squirrel-y handling.
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[scottyrocks]

30 in the front is gonna feel like a buckboard.
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