The Corvair example is an extreme - and necessary - one. I learned to drive in a WWII surplus Jeep and a 1960s Corvair. Before I drove my aunt and uncle’s Corvair I read the owners manual. At age 16 I admit I was not really conversant with checking tire inflation, so I drove it without regard to that issue. I did encounter a broken fan belt / overheating condition. I pulled over stopped the engine, and turned the heater to High. I crept back to town, paying attention to the temp gauge, and stopped at the local Chevy dealer, who replaced the belt and charged it ($9, IIRC) to my uncle.
The Corvair was particularly and extremely dependent on owners and mechanics knowing its tire inflation parameters. The Corvair was one of - maybe the biggest of - many factors that contributed to the present requirement that new cars have tire pressure monitoring system.
I was not there when the bill was being debated but I believe that TPMS was intended to warn of a tire pressure variance that presents a danger of substandard handling or the hazard of impending catastrophic pressure loss. The warning usually comes well before CPL. That’s why it is rightly called a warning and not an announcement.
@wesw, not always true. I don’t have TPMS on my 2000 Explorer, but the rear of the truck is such that if the tire is down to 10 PSI, you cannot tell by visual inspection unless you have a load in the back. However, the rear end gets way unstable. I just had that problem, wound up having to dig around for 4 quarters to use the gas station pump because I was a ways away from the house when it happened. The tire shop found 3 nails in the tire, two causing leaks. And, this is from a guy that checks his tire pressure monthly and anytime the tires look suspicious. I would have liked to have a warning light come on versus a ‘wag-the-dog’ feel at 70 mph.
Another vehicle that has more recently come under scrutiny than the Corvair is the Ford E-350 15 passenger van. There have been roll-over problems with these vehicles. The university where I taught had an E-350 roll over and one student was killed. It did turn out that the students were doing something stupid–changing drivers while the vehicle was traveling down the highway. However, the university took these vehicles off the road because the insurance company did not want to insure them.
My son was in his sophomore year in college and was doing an internship in Appalachian area and was driving these 15 passenger vans through the mountains with children on board. I told him about the problems and he said that if the driver uses good sense and realized that the vehicle wasn’t a car there was no problem. We did make a trip to visit him and I rode with him while he transported children. He wouldn’t even start the engine until he had checked to see that each child had secured his or her seatbelt.
I did own a Corvair–a 1961 model. I installed a camber compensating transverse rear spring between the swing axles and set the tire pressure according to the manual and I thought the Corvair was one of the best handling cars I ever owned.
I owned a VW and a Corvair. Both had the swing axle design and I didn’t find any handling problem with either one of them. I believe after 64 they just added a rear stabilizer so the wheels couldn’t bend so far. I had a manual for the VW and read it. It actually had a lot more information than most manuals like to not brake while turning to save on the brakes. I don’t recall if I had a Corvair manual but did have a Chiltons for it. Again I don’t recall ever reading having that severe difference in tire pressure fromhe front to the back. Had I known it, I may well have ignored it as being absurd. Certainly there was not tire pressure differential in the VW. They were all the same. Personally the Corvair I think got a bad rap, and really I’m not sure what good it would have done to have a visor notice with the tire pressures without also having drivers and mechanics take a class. It was just different technology that the public didn’t understand and drove the things like a sports car instead of an economy car.
Is there any end anymore what is blamed on engineers and manufacturers instead of the people applying common sense to using machines?
shanonia said: “I was not there when the bill was being debated but I believe that TPMS was intended to warn of a tire pressure variance that presents a danger of substandard handling or the hazard of impending catastrophic pressure loss. The warning usually comes well before CPL. That’s why it is rightly called a warning and not an announcement.”
Well, I was there and the reason TPMS was mandated was because of low inflation pressures. NHTSA did a study and 25% of the vehicles on the road had at least 1 tire dangerously underinflated (by their defnition) - just like the tire manufacturers pointed out. Since the technology was available, but no one seem to be using it, the Feds decided to require it.
The Feds also required the vehicle manufacturers to post the vehicle tire placard (the sticker that has the specified pressures) in the same location - the driver’s doorframe. Previously its location wasn’t specified and there were at least 4 different locations where it might be found.
Rather than the Feds choosing TPMS, I would have preferred to see the use of the existing ABS wheel sensors used as a means of detecting low pressure tires.
@capriracer Thanks for the professional information on tires. They are a mystery to some of us. I read several of your sections and they were very informative. If I could make one small suggestion, it would be ending with a short paragraph on your opinion such as “in my opionion the proximate cause of the Explorer problems was the tire manufacturing process at one plant causing tread separation exacerbated by owner neglect”. Or something. A good discussion but then at the end wasn’t sure of the conclusion. Like most things, it take several items of failure together to create a problem.
“than the Feds choosing TPMS, I would have preferred to see the use of the existing ABS wheel sensors used as a means of detecting low pressure tires.”
What you’re talking about is called indirect TPMS, and it sucks
It doesn’t let you know the actual tire pressures. All it does is compare wheel speed signal, and it uses that information to determine if one tire is drastically lower than the others
Where it falls FLAT ON ITS FACE is if the driver is a doofus who never checks his tires. You might have a situation where the sticker says 32psi, but because doofus driver never checked the tires, they’re all now at 15psi. Because all wheel speed signals are the same, no problem is reported
^Does a so-so system, that by its nature lasts the life of car, qualify as better, or worse, than a more sophisticated system that is inop from year 5 (when the batteries die) until whenever the car is crushed?
The negligent doofus you mentioned isn’t likely to know, or care, what the TPMS icon means. Heck, he may have bought the car 6 years’ old and just assumed it is supposed to be there.
I prefer it because it’s simple, inexpensive, maintenance free and reliable. It works extremely well for the cases where the pressure of one of the tires becomes different than the rest.
I am not worried about all four tires loosing pressure uniformly over time, since those occurrences are rare enough to not warrant the TPMS system in use today.
My car has an indirect TPMS, and to me it’s fine. The probability of all four tires losing air at the same rate is infinitesimally small IMHO. Its weakness is that it has no way to monitor the pressure of the spare tire. However, since spare tires are becoming a thing of the past anyway…
Ironic, isn’t it. The feds mandate a system to babysit our tire pressure but accept “doughnut” spares, and even accept no spare. IMHO “doughnut” spares are unsafe in bad weather and, considering the potholes we in the snow belt have to live with, anywhere north of the 43rd parallel. I, for one, would not want to have to put a doughnut on in a blizzard. Or hit a pothole with one. I realize that the TPMS mandate was a result of the Explorer disaster, but jeeze.
Honda has apparently thrown in the towel on their direct system because of in-tire sensor problems and cost and is switching over to indirect (e.g., the new Fit and Accord).
With stability control systems now mandated, it would seem logical to use the wheel speed sensors for the TPMS too. That might be behind the Honda change.
I dunno. I haven’t had any problems with the TPMS and really prefer having individual readings. I often just take a look to see if anything is going on. In the north country though, a tire can be fine when its 80 degrees out but when it gets to 10 below it can be way under inflated. All of them would be similarly under inflated. Its just handy.