Tire static electricity?



Tom and Ray remember vividly the static caused by tires 20 years ago. But guess what; the tire companies heard about it and took steps to correct the problem! This should not be an issue now.

I get static from my car, not because of the tires but because I move on my cloth seat. It’s worse in the wintertime when the air is dry.

There is some relief possible by spraying anti-cling (anti-static) fabric spray on the seats.

You can find anti-static spray at the computer store.  You can even try spray starch.


Within the past year or so, there was a fatal explosion at a local convenience store’s gas area because of a spark from someone filling his tank. Soon afterward, I was filling my tank and remarked to the person next to me about the explosion. He told me that before I fill up my tank, I should always touch the outside of my car to eliminate any static I might have brought to the outside. I was wondering, can static electricity in a car be fatal? And, is touching your car’s outside the solution?


Tom and Ray, You didn’t really explain why new tires would create more static electricity than older tires. Are some brands or models of tires worse than others?


My brother and sister in law recently got new tires at a “membership discount” store and now they have the same problem. I can’t get out of their cars without getting a huge (1") painful spark. Wasn’t a problem before but now it is.

Rubber is a very good insulator so impurities have to be added to allow charges to bleed off in a reasonable amount of time. As mentioned earlier, tire manufacturers have solved the problem by doing this but I have to wonder if they aren’t leaving this feature out for retailers who are beating them up over price.


It’s already been pointed out that the static charge is generated when you slide across cloth seats getting out of your vehicle. But the charge isn’t building up on your vehicle, it is building up on you. Because the tires have a compound that makes them conductive, any charge on the vehicle bleeds off to the ground. But with your rubber soled shoes, you are insulated from the ground and the charge bleeds off more slowly to the air. If you then touch anything else that is grounded and conductive, like your car door, the charge bleeds off very quickly and you get shocked.

There is a very simple and effective way to prevent this from happening, and it doesn’t involve dryer sheets or anti-static spray. All you need to do is to maintain contact with a conductive part of your car while you get out of it. The metal door frame works somewhat, but being painted, it isn’t the best option. If you have any bare metal or chromed parts that you can easily keep one hand on, this will work better. The way this works is that by grounding yourself, no static charge can build up on you as it will be drained away while it is being generated and before it can build to a level to deliver a nasty jolt.

I’ve used this method for nearly 20 years and it works every time. My only problem is that newer cars don’t have much in the way of chrome or bare metal parts to hold onto, and now I have to make do with keeping a firm grip on the painted door frame, so I occasionally feel small shocks as the charge builds up enough to overcome the insulation of the layer of paint.

To answer the question of old tires vs. new tires, the only answer must be conductive vs. non-conductive. If your tires are non-conductive, then they will insulate your car from the ground. In this scenario, you get out of the car and acquire a static charge from sliding across your polyester blend seats. You touch your car and some of the charge from you transfers to the car, but since the car is insulated from ground, the charge doesn’t flow to ground and you don’t get a shock, or possibly a minor one.
On the other hand, if the tires are conductive, then the car is always grounded through them. When you get out of your car and build a charge, touching your car allows that charge to flow directly to ground very quickly resulting in you getting zapped.

For this reason, I have serious doubts about the grounding straps discussed on the show having any positive effect on this problem, since the tires are already conductive.


When my mother started using a wheelchair following a stroke (and because her left hand was affected, she couldn’t really propel it herself very far so I ended up pushing it), we discovered that whatever they make the tires out of builds up one heck of a charge rolling on the linoleum floors of shopping malls. Every time Mom would turn her head she’d draw a spark in the ear from my hand on the grips.

Tried to find grounding straps at truck stops and auto stores and nobody seemed to have any idea what I was talking about. Finally stumbled across a chain-metal dog collar at a dollar store, attached it to the frame under the seat and adjusted the length so the final link just barely brushed the ground (didn’t need to get it caught on an irregular spot on the floor and send her pitching forward as the chair screeched to a halt).

Sparking problem solved, and for only a buck!


Just an FYI.

What causes the build up of static electricity in tires is the use of silica in place of some of the carbon black in the tread rubber. Obviously the more the silica, the bigger the problem. But silica also reduces rolling resistance, so there’s a good reason to use it.

To combat the static build up, many tire manufacturers have taken to putting a small strip of carbon black only rubber in the center of the tread. You can sometimes see this as the black only rubber is more black. (Did I just say that???)


Here’s some more information about static electricity and gas station fires. There have been documented cases, though it’s not a common problem. Snopes.com had a good article about it:
There is no truth to the canard one may encounter in e-mail about cell phones causing gas station fires.


I knew of the the discharge straps they were talking about but have never tried to get one. I may have to try for my brother and sister in laws cars. The quarter thing is a good idea but holding onto the body of the car while getting out is much better. That is if you remember to do so. The time I remember is after getting zapped (self cleaning brain:)

I was in Switzerland back in the 90s and all their cars had one. Didn’t know why but now I suspect that they were dealing with this issue back then. A side benefit to one of these things is that your radio may work a little better if you listen to AM. Getting a better ground results in a better received signal. Probably won’t do much for FM but may give a slight improvement (oh great, another experiment to run).


Actually, pure rubber would make lousy tires. For the last hundred years or so, tire makers have used carbon black as a “filler” that stiffens and strengthens the rubber. It just happens to make the tires conduct electricity (not a lot, but enough to control static). As a later comment points out, silica is an alternate filler that they started using 20 years ago, and silica does not conduct electricity. That is when the “tollbooth problem” first cropped up.

But to answer the above point, I doubt that silica is less expensive than carbon black; it’s used in premium tires. It does great things for the tire (other than the electricity problem) - but you probably won’t find the cheapest tires made with only silica filler.


A little more background.

Silica is indeed more expensive than carbon black, but not enough to worry about - and certainly not enough to be the difference between the price of tires.

Where the problem lies is in making some part of the carbon black load rubber in contact with the road surface without appreciably affecting the silica loaded rubber. This requires some specialized manufacturing equipment - and the difference in price is more or less a reflection of the increase in quality. And certainly, low end tires would be made in plants without this equipment.


My Civic has been trying to give me static shocks since Day-1. The solution is so simple that I don’t even think about it any more. As soon as I put one foot on the ground I automatically lean my leg lightly against the metal at the bottom of the door. The spark discharges, but I don’t notice it unless I’m thinking about it. Another solution, since you still have the keys in your hand, is to touch a key to the car when you get out. You may hear the spark, but you won’t feel anything if you are holding the metal part of the key tight.