Tire Pressure

On my 74 super I usually run 35psi all around. I probably have the fronts a little over-inflated, but I have never noted any abnormal wear so I just leave it at 35.

I think(I could be mistaken) that the pressures listed on the glovebox door are for bias-ply tires. All I've ever run is radial tires.

Chris

Nope, follow the recommended pressures -- and don't trust the tire boys to remember!

Most Detroit iron has a fairly even weight distribution pattern, squaring the car's weight between the front and rear. Beetles only have a third of the curb weight riding on the front tires. Overinflating the fronts has the effect of changing your 165/15s into 95/16s -- not enough weight to maintain full footprint contact with the road.

This concept will be painfully obvious if you live anywhere with wind. You think Chicago is the windy city? Try Amarillo TX. Last time I put new tires on my '74 Super, I specifically asked them to inflate to 18psi/29psi. They didn't, putting in 32psi all the way 'round. I hit the freeway and grabbed the next exit as a relatively calm15mph crosswind made the car undriveable.

Jim O'Malley /

Follow your Owner's Manual to the letter!

I've read too many warnings about how you should never inflate your tires to a higher pressure than what VW says, ESPECIALLY THE FRONT TIRES!!! It's DANGEROUS!!! You've been WARNED...TWICE.

GEEEEZ!!! You're running at 35psi all the way around??? Are you suicidal???

You're tires are probably rated at a maximum of 35psi. That's fine if you're just going to leave it parked in the garage or in the shade.

You put yourself in the car and the pressure goes up. You drive for more than a couple of minutes and the pressure goes up more. You're probably driving around with close to 38psi in tires rated at 35psi.

Where in the world did you get the idea that this was an OK thing to do??? Why are you intentionally ignoring the safety ratings of your tires and the car manufacturers recommendations???

Calm down, dude!!! Next step is for your post to be in ALL CAPS!!! When you use multiple !!!!!!!s and ?????s you come off as frantic and/or annoying!!! NOW EXCUSE ME WHILE I GO PUMP MY TIRES UP TO 40 PSI ALL AROUND!!! ps- You misspelled "your." Think about it... "you're" = "you are" "You are tires are probably rated at....." Question: Does that make sense? Answer: No.

"Stupid people are funny." - me

Here:

Kumho Power Star 758

for your 1974 Volkswagen Beetle Load Rating: SL

Size: 165/80TR15 Blackwall

TR Speed Rated Price: $26

Estimated Availability: In Stock

Kumho usually makes excellent racing tires, and I have heard good reviews of them.

Lynn

1974 Superbeetle

Ok, Ok! I get it! :-)

I got them back from the auto place, and of course, they all had 32 psi in them. I deflated the fronts to 18, and the backs to 29.

Lynn

1974 Superbeetle

The 18/29 psi applies to the original equipment bias ply tires only.(which you don't have anymore) Radial tires have always required more air pressure than the same size bias ply tire. 18 psi in a radial tire would be dangerously low. Radial tires are not supposed to have a bulge in the sidewall when you look at them from the front or back like a lot of people seem to think. On the other hand max pressure(35psi) for a radial tire that size would be a bit too much unless you were carrying a ton of extra weight. You'll probably find that mid twenties in the front works well.

The Bentley Manual (1970-79) sez:

------------------------------------------ Conventional Tire Inflation Pressures (Bias ply):

Beetle, Ghia, to December 1972; 1970 Convertible; With 1-2 persons - 16 psi Front, 24 psi Rear; Fully loaded - 17 psi Front, 26 psi Rear

Super Beetle, Convertible from 1971 up to Dec. 1972; With 1-2 persons - 16 psi Front, 27 psi Rear; Fully loaded - 18 psi Front, 27 psi Rear

All models, from Jan. 1973; With 1-2 persons - 18 psi Front, 29 psi Rear; Fully loaded - 18 psi Front, 29 psi Rear

--------------------------------------

Radial Tire Inflation Pressures (Radial ply)

Beetle, Ghia, to December 1972; 1970 Convertible; With 1-2 persons - 18 psi Front, 27 psi Rear; Fully loaded - 18 psi Front, 27 psi Rear

Super Beetle, Convertible from 1971 up to Dec. 1972; With 1-2 persons - 18 psi Front, 27 psi Rear; Fully loaded - 18 psi Front, 27 psi Rear

All models, from Jan. 1973; With 1-2 persons - 18 psi Front, 29 psi Rear; Fully loaded - 18 psi Front, 29 psi Rear

- NOTE: Increase the pressures in conventional bias ply tires by 3 psi for prolonged high speeds but never exceed the maximum tire inflation pressure designated on the tire sidewall.

Glove compartment in my 74 super sez 18/29 for bias and radial. I was just wondering if these values were right or not. Probably wouldn't hurt to have mid 20's pressures. But it would probably drive like a tractor any higher.

Thanks for everyone's help!

Lynn

1974 Superbeetle

dude calm down..its obvious you are no tire tech so maybe read your sidewall sometime...the max psi is listed as a cold temp....this pressure is set with a tollerance for an increase in pressure due to heat....it is not uncommon to gain up to 5-6 psi in summer weather on the interstate, and the tire manufacturers know it.....so don't have a stroke, your point is not only wrong, but basically pointless....(BTW "put yourself in the car the pressure goes up" is incorrect too...the max weight is also what the max pressure is designed for...sheesh...)

So Joey, are you saying the tire manufacturer knows more about the air pressure I should have in my tires than the car manufacturer knows? Hardly!

My point is 35psi is a lot of pressure over the recommended front tire pressure on the car. Are you saying this is OK? Because it's not. It's flat out dangerous. It's almost double the recommended pressure. It's unsafe. It's WRONG!

So don't tell me my point is wrong.

Lynn, the pressures you posted are right. Mike is making up nonsense.

The sticker is correct. You could add a couple of pounds to each, especially if the car is heavily loaded, but don't inflate it the same as your Chevy. The reason the front tires get so little pressure is that they have so little weight on them.

-

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

-----------------------------------------------

Oh, and the max pressure isn't listed as a cold temp, it's listed as a max pressure. Max means max.

The normal car manufacturer's tire pressure recommendation is the cold inflation pressure you're thinking of.

Yes, while driving it's not uncommon for the tire to gain pressure in the summer weather or in cold weather either. And that was my point. If someone is foolish enough to air up their tires to the maximum then they have no leeway for normal pressure increases due to load and friction.

You also said, ""put yourself in the car the pressure goes up" is incorrect ".

Who are you trying to BS? Of course the tire pressure goes up as the load increases. You're talking nonsense.

Since you don't think tire pressure goes up as the load goes up you definitely don't know what you're talking about.

If I air up my tires to the car manufacturer's recommended pressures and then I put 400 pounds of people in the car obviously the tire pressure goes up.

I may have been wrong for years... I learned ( I think from the AA (AAA) ) that before a long journey, to put a couple of extra pounds in your tyres. When they warm up, they soften and need more air.

As for loading up your car, 'my' thoughts were, a given volume of air in a given space, give a constant pressure. For it to go up 'much' when you load the car, you would have to see a serious flat spot (less space) on the bottom of the tyre.

I havent looked recently, but I thought the MAX pressure was like 135psi or something way up there ?

Just my thoughts

Rich

Dan Smith wrote:

Air is a gas, which when heated, expands. On race cars, tire pressures are sometimes critical. You put a certain pressure in the tires before the race, and when you immediately measure the tire pressure during the first seconds of pitstop, you will find that the tire pressures have increased by 50% easily. Granted, in that environment the race slicks also get much hotter than you'd ever see your street tires get...

Jan (Race car mechanic)

...................Correct! And if the front tires are larger than the std.

165's, they should have less pressure, not more. My '77 has 185/65-15's on the front and I've been running 16 psi for about 10,000 miles now. These tires are wearing evenly and handle superbly even when cornering and braking hard. With no front bumper, There is only about 425 lbs. load on each front tire which is way way below the load rating of these tires. A tire's cross-section shape is determined by the load and the pressure working to counteract the other and less load always requires less pressure to maintain the optimal shape that maximises the contact patch on the pavement while not sacrificing the structural integrity of the tire. Formula 1 racing cars use less than 25 psi on the front tires I read somewhere because they have large profiles and only 200 lbs. load per front tire at rest and still only about 800 lbs. load per tire from the downforce generated by the wings & spoilers that are used to increase traction at 200 mph! The worst aspect of this 'theory' that the front tires on a bug should be inflated to the twenty or thirty psi range is that the tread's grip during braking and cornering goes way down. I've done a lot of 'seat of the pants' experimenting with this question over the years and I drive like a maniac sometimes. This goes beyond everyone's right to their own opinion for me because I've seen through direct experience that overinflated front tires on a bug are a direct cause for loss of control at high speeds when cornering and braking. When the road is wet, this loss of tire grip from overinflated tires is even worse.

It was overwhelming for me when I first saw the listed tire pressure for my '66 bug. I had to question the settings also, when I was used to inflating the tires on my other vehicles at 32 psi. I'm putting in 20 psi front, and

28 psi rear in my Bug. My car handles better and rides a lot smoother at these tire pressures, however I'm not a racer and never intended to drive the VW fast. Rob and Dave's VW website have experimented with tire pressures, I also got to speak with Rob by phone not only on tires but other related VW matters as well. I really like Rob for his expertise and honesty on VW's. Since he's done most of the research, I'll trust his recommendations.