Is there a product that can permanently balance your tires and give you 25% to 50% more miles? Yes there is, and truckers have known about them for YEARS. Centramatic has been around for a long time and have a proven product.

I first saw this product a few years ago and thought it was a neat idea. However at the time I thought to myself, “I don’t need those, my tires are balanced well, and big O will balance them anytime”. That worked ok for near stock size tires.

However as I spent more and more time around the offroad world, the bigger and bigger the tires got. When I got started in this around 1989, Only mud trucks and show trucks had anything larger than 33s. The common size up until around 94' was 32inchs for trucks and jeeps. That size is not to hard to balance. Now we are past 35s up into the 37” and 40”s. These can be a real challenge to balance. They also tend to change their balance quite a bit with a little wear. There is a lot of rubber out on the tread and a little weight variation makes a BIG difference.

Chunk a few lugs of rubber on a rock and you could be 1/8 ounce lighter at the tread. This translates to more than 1/8 balancing weight on the rim. If the rim is a 15 inch rim and the tire is a 30 inch tire, the weight to balance it is 1/4 ounce. If you have a 35 inch tire on a 15 inch rim the balancing weight to compensate for a ¼ ounce difference is more than ½ ounce at the rim. You can see how a little bit of rubber missing can make a big difference on a larger tire.

I lifted my truck and then I acquired 35” BFG mudders about six months ago. While this is an old tread design, originally released in 1980, they have come a long way in rubber compound and manufacture of the tires. This has allowed them to build a 35” tire that wears and rides well on the road, and works well off road. A tire only dreamed of in the 70s and 80s.

I had them mounted and balanced and they rode well, for a while. As the tires broke in they started to change how they rode. I had them rebalanced. And they did well for a while…. I started thinking that this was going to suck. Then I remembered Centramatic.

What Centramatic is, is an on the wheel tire balancing system. It consists of a metal plate and tube/ring with balancing media in it around the outside of the plate(more about how this works later) . This goes between the wheel and the hub. The unit will balance the tire while it is moving and will continually adjust as you drive. This does much more than just balance the tire though. It will help increase the life of the tire and improve tread wear.

Here is a video of how its made.

http://www.centramatic.com/Demo/video1.mpg

I painted them to hide behind the wheel, and painted my hubs as well. (Why not?)

You cant even see them installed.

The ride was immediately improved. I could do 60mph now without the hood jumping up and down. It was still not a very good ride though. So I went to Discount Tire and had them check the tires on their Hunter machine that reads the roundness.

Big disappointment, all four tires were out of round. Two tires were suggested to be replaced. One tire had three hard spots in a triangle pattern. Unfortunately I got the tires from a person who won them in a raffle and could not return or exchange them. Be best they could do was measure the tires and rims and rotate them to minimize the highpoints.

Again major improvement. I can now drive highway speeds with very little vibrations. I like having the tires now, and I enjoy knowing that as my tires will stay in balance as I run them bald, unevenly chunking the lugs on sharp rocks, with globs of desert clay and rocks inside the rim and in the tread.

OK now for the part were I explain how they work and what they will do for your tires.

How they work

Here is a great link to a video on the centramatic webpage, it shows how they work.

http://www.centramatic.com/Demo/video2.mpg

Inside the ring is a mix of oil and lead alloy “BB”s. (for lack of a better term).   As you drive, these BBs distribute themselves around the ring. (there is about nine ounces of weight)   As you drive the tire starts to deflect (bounce).   This deflection causes the media to move in the ring.   The media will continue to move until the tire stops deflecting.   When this happens the tire is in balance!   This happens very quickly and unnoticed.

It takes some speed to get the media spread out, about 25mph.  However at this speed and below, balance is not an issue.   You may hear the media “slushing” at low speeds.   As you get above 25 mph you will have enough energy to start the media moving around to balance the tire.   As you go faster the tire will already be balanced and will continually fine tune the balance as you drive.   As you slow down you will notice you can get down to about 10 or 15 mph before the “slushing” sound comes back as the media falls to the bottom.   Although I can hear this with my doors off, you may not even notice it.   My wife doesn’t, and I tried to point out the noise to a friend and he could not pick it out.

Great. So what does this do for my Tire….

Well for one, it can keep the tire cooler at highway speeds.   As an unbalanced tire (even an unperceived imbalance) rotates at speed, the sidewall will deflect causing heat.   Also the contact patch at the point of deflection gets more wear and more heat due to the extra pressure on the tread.   This point of contact and deflection does change with speed.   If you have ever seen a tire on another car bouncing way up and down you can imagine the forces and temps involved.   This happens when the weight and the deflection (bounce) of the tire coincide on the “up” side.   As you may have noticed at one time or another if you speed up it seems to smooth out, well it really doesn’t.   All you are doing is putting the energy into the tire (heat) and rotating it around before the deflection and the weight push the tire up together.   So the weight may be almost at the top of the tire before the deflection starts to push the tire up.   This puts wear and heat in other spots than the off balance point.

So now we know how an off balance tire can heat up odd areas of the tire tread and sidewalls.   Heat kills tires.   It hardens the rubber on the tread and can lead to belt separation, among other things.   Ford tried to blame tire failure on the Explorers on low tire pressure causing excess heat, leading to tire failure.

Soooooo, if we run a cooler tire that is in balance minimizing tread wear, will it last longer.  YES IT WILL!!!!!!   About 25% to 50% more life out of a tire.   There is a Steer Tire (term used on “big rigs” front tires) with over 200,000 miles on it with useable tread still left on it! (100K is typical on this tire).   I know of a set of MTRs with over 30k on them on a H1.

What can I do to help all this?

It may sound silly. Have the tires checked for roundness, and have them well balanced before you install the centramatic.  

“Why balance? I thought that was the centramatics job?”

Well it is.  However, if your tire is well balanced to begin with the more the centramatic can compensate for.   If your tire is at the limit of the unit (around nine ounces) how can it compensate for mud on the part of the tire with the extra weight.   Having the tires roundness checked and taken care of is also important.

So we know what they can do, what cant they do?

They can not fix an out of round tire, not completely anyway.   A tire with a hard or high spot will cause deflection, this will cause the media to move to counteract it, and it will to a point.   However the harder you hit a high point or hard spot the sharper the result.   You can not “balance” out a bump.   An out of balance tire is a smoother movement, like a wave.   (The resulting feel is different due to shocks, the road, and deflection) Think of an out of round like gluing a rock on the tread.   No matter how much weight you put on the other side it will bump the tire upwards.   Now imagine two or three hard spots.   An out of round can be in perfect balance, but have one or more hard or highspots.

If you have a minor hard spot that is under say eight ounces of force, the centramatic can help smooth out the tire, even may help wear down the hard spot.

They will also let you know if a wheel bearing is going bad or is loose. The movment of a loose bearing will cause the media to unevenly disperse and your tire will vibrate.   Of you have a set on and a tire starts vibrating, check the wheel bearings.

One more big ‘NO NO’. Do not spin the tire up to speed on a jackstand or the like. The tire will not have the deflection of the sidewall to disperse the media. It will cause the media to just lump up on one spot and cause the whole axle to start bouncing on the stand. The cure to this is to remove the centramatic on that axle before you spin up the tire.

Are there other things available?

Yes there is. Some are commercial other are home brew. Stay away from the home brew!

One company uses a similar idea, with a plate and ring filled with mercury. It works on the same idea but costs much more money.   Also, if you are in an accident and bust one, you have a liquid mercury spill.   The centramatics have lead alloy shot, but is not going to really go anywhere.   Mercury is not called “quicksilver” for nothing, and is extremely toxic.   Lead can be toxic, but the government gives licenses to hunters who shoot lead bbs in fields and forests.

Then there are the powders.   Power is inserted into the tire.   It works on the same idea.   The power will be moved around by the deflection of the tire.   There are many “things” that people have put in their tires to replicate this idea.   Among theones that I have heard of are bbs and antifreeze, golf balls, lead shot and antifreeze, ball bearings…. The drawbacks of these are numerous.

The material in the tire can damage the lining. (The powder manufacturers have engineered the powders to do minimal damage).   The powders can freeze if moisture from a compressor builds up in the tire.   They recommend a water separator on the air line to dry the air going into your tires.   They tried to minimize moisture absorbsion with polymers, but if enough builds up it will freeze.(hence the antifreeze in the afore mentioned bad homebrew ideas).   When it freezes you have a 8 ounce block in your tire.

Also when you use powders (or the other Ideas) you cannot spin balance the tires on a machine.   If you get a flat, you may have to replace them.   You cannot easly remove the powder, or change tires and keep the rims on the vehicle….. they go with the tire.

With the centramatic you can move them to another Jeep as a diagnostic tool, or move a tire to a different location on your jeep to check things.

I like Centramatic and I strongly recommend it to anyone who runs larger tires, wishes to save money, and likes a nice smooth ride.

9-20-2005