By Rick Dill, Geoff Fleming, David Jones, Bud Osbourne, Al Zim, edited by Barry Lee Brisco
[Editor:] When new the 356 came with tires that required tubes, because that was standard at that time. Wheels back then did not have the "safety bead" that has been standard on wheels since the late 1960's. That feature was purported to reduce the chance of a tire coming off the wheel during a blowout (for the 1968 model year Porsche incorporated a "safety bead" on their steel wheels though the optional Fuchs alloy wheels did not get this change until 1972). The consensus among long-time 356 owners is that it is not necessary to use tires with tubes even though the original 356 wheels do not have the "safety bead". Below are comments from several of them.
Rick Dill: Now the real truth is that tubes will blow out at least 10 times as often as tubeless and that is what rolls over the SUVs and occasionally a 356. So even if the tire isn't as well contained because of no "safety bead" on the rim, it is far less likely to cause damage if it is tubeless because it will go down slowly, and unless you really aren't paying attention and have power steering (obviously not if you're drivng your 356), you will recognize a soft tire. So, if the rim holds air then you should go tubeless. It is that simple. Then, of course, don't drive over fallen logs, rocks, or similar obstacles at speed.
Geoff Fleming: Tube tires are rarely used today. I would say that 99% of 356 owners use modern radial tires. In the So. Connecticut Registry, no one uses tubeless tires and our cars are driven some long distances at modern highway speeds. No 356 rims have such ridges [the "safety bead"] and all 356 rims accept tubeless radial tires. After more than 250,000 miles of hard driving I`ve never had the slightest problem with tires/rims. Forget the tubes: this is the 21st century.
David Jones: My personal opinion based on 45 years of experience is that tubes are not necessary. I replaced the tires on my 62 VW Bug in 1964 with Michelin X. The originals were Continental cross plies [with tubes]. The tire shop said that tubes were not necessary. That bug was retired at 180,000 miles and new tires about every 30,000 miles, always radial and a mix of Goodyear, Pirelli and Uniroyal. This was Europe, Germany and the UK where tires get a good workout every day. 30,000 miles was good mileage for a set of tires. I never so much as had a flat and though driven everywhere using the gas pedal as an on/off switch never pulled a tire off a rim. Fast forward to 1980 and Formula Vee racing. Using VW rims and both bias ply and radial tires the only time I pulled tires off rims was by unintentionally traveling sideways off the track and digging in the loose gravel or dirt off the track. The excursions were never as a result of the tire going down. Some of those later VW rims had the safety bead but going sideways though the tulips at 100 mph the safety bead did not help. I think the safety bead is there to help retain the tire if one is unlucky enough to drive around on underinflated tires which of course is not something any 356er would do. I have done autocrosses in my 356's and also a hillclimb and the tires were tortured to well past anything one should normally subject them to on the road and so far never a problem. Safety beads were put in place to protect people from their own stupidity. Tubed tires were state of the art before the advent of tubeless tires. Tubed tires pretty much go flat in an instant if you get a nail through them. Tubeless tires can hold air for a long time till you remove the nail. Tubeless tires weigh the weight of the tube less then tubed tires! Bud Osbourne: Tubeless tires have been around for a whole lot longer than wheels with "proper ridges" [the safety bead] for mounting tubeless tires. As long as they're kept properly inflated, "no worries".
Al Zim: I have forgotten exactly what year American made cars came with tubeless tires. My guess is 1955. This was fostered by the manufactures not having to install a tube as the mounted millions of tires each year. We can assume that 1955 and 1968 (when the safety rims were first used on Porsche) tens of millions of cars were produced that used tubeless tires without the use of safety rims. Now here comes our buddy the United States Government to help protect us from ourselves. In their infinite wisdom they realized that most drivers did not take care of their tires. So they made a rim that would hold the tire if it was low on pressure. Originally all they wanted to hold on was the inside of the rim. So the bump was only on the inside. Later in about 1972 they put the bump on both sides of the tire. With the 5.5 inch 911 rim I believe the bump was on the inside. The early Fuchs wheels did not have the bump because they were for tube type tires. The switch from the deep dish to the flatter wheel reduced the diameter of the valve stem and produced a wheel with a safety bump on both sides (I think). I believe both the 5.5 and 6 inch steel wheels had this.