How to Use a Bubble Balancer on a Car Wheel: Leveling, Weights and Checking

A bubble balancer comes with a short manual or with none. The clearest one we found belongs to the Ranger RWS-1B, a bubble balancer sold by BendPak, and this page follows it step by step. Your balancer may differ in details such as the leveling screws, so read its own instructions too. We have not balanced wheels ourselves for this page; every step below is taken from the documents listed at the end.

What you need

• The balancer and a firm, stable place for it. The Ranger manual names a firm stable surface or floor.
• Wheel weights in several sizes. The method works by trying a weight and swapping it for a heavier or lighter one.
• A wheel that fits the head. The RWS-1B is specified for hub holes from 1.5 to 4.5 in. in diameter. The Harbor Freight store model is stated for hubs from 1-1/2 to 4-1/4 in. and wheels up to 15 in.
• Chalk, if you use the four-weight method further down.
• A tire that is mounted, seated and inflated. Balancing is the last station of the job described under how to change tires at home.

What the tool measures, and what to check before buying one, is on the parent page about bubble wheel balancers.

Step by step

1. Level the bare balancer

   Set the balancer on a firm, stable surface. On the RWS-1B the level is held by three mounting screws: turn them until the air bubble is centered in the black circle. According to the manual, tightening a screw moves the bubble away from that screw. Do this before any wheel goes on.

2. Prepare the wheel

   Take the wheel off the vehicle. Remove any old weights and clean debris from the inside and the underside of the rim. Check and clean the center hole of the rim, because the wheel has to seat evenly on the cone.

3. Set the wheel on the cone

   Place the tire and wheel on the balancer and check for uniform seating where the rim meets the cone. Let the wheel settle to a stop before you read anything.

4. Read the bubble

   An out-of-balance wheel moves the bubble outside the black circle, in the opposite direction from the heavy side. The side of the rim closest to the bubble is the light side.

5. Find the weight

   Place a weight on the light side of the rim closest to the bubble. If it does not bring the bubble back to the middle of the circle, try a heavier or a lighter weight until the bubble settles in the center.

6. Split and attach the weight

   Remove the wheel from the balancer. Attach the amount you found on both sides of the rim at the same location: half on the outer edge, half on the inner edge. The manual's example is a required 3 ounces, attached as 1.5 ounces outside and 1.5 ounces inside.

Why the weight is split

A bubble balancer finds one heavy spot with the wheel at rest. That is static imbalance, the kind the tire makers' care manual describes as vibration from up-and-down movement and as correctable with a bubble or a spin balancer. The manual gives no reason for splitting the weight. Our reading: half on each edge keeps the correction centered across the width of the wheel instead of loading one side.

It does not turn the bubble balancer into a two-plane tool. The same care manual says the second kind of imbalance, an uneven spread of weight across the wheel that shows as wobble or shimmy, can only be corrected using a dynamic spin balancer. The difference is the subject of the page on static vs. dynamic balancing.

The four-weight method

The Ranger manual describes a second procedure it calls the optional A-B-C method. It uses four equal weights instead of one.

1. Lay four weights of the lightest size on the light side, in two pairs. In each pair one weight sits on the rim flange and the other directly behind it.
2. If the bubble does not move to the middle of the circle or beyond it, replace all four with the next heavier size, and again if needed.
3. Move the two pairs apart, in opposite directions around the rim and by equal distances from the starting point, until the bubble is centered.
4. Draw a chalk line on the tread in the middle of each pair.
5. Lift the wheel off. Attach one weight of each pair on the inside, the underside of the wheel, in line with its chalk mark.
6. Put the wheel back with the outside face up, lay the remaining two weights at the chalk lines and move them slightly apart or together until the bubble is centered. Then attach them to the outside of the rim flange.

The last step is also a check: the wheel goes back on the balancer with half of the weights already fixed, and the bubble shows whether the rest sits right.

When the bubble will not center

The manual names one case in which weights may not balance the wheel: the heavy portion of the wheel and the heavy portion of the tire are on the same side. Its remedy is to deflate the tire, rotate it approximately half way around the rim, reinflate it and repeat the process.

Checking your work

The basic procedure in the Ranger manual ends with attaching the weights. Putting the wheel back on the balancer afterward costs a minute and shows whether the bubble still sits in the circle; that recheck is our suggestion, taken from the last step of the four-weight method.

What a centered bubble cannot tell you is whether the wheel is free of the side-to-side imbalance that only shows when it turns. If a wheel shakes at speed after a static balance, have it spin balanced. How far a bubble reading can be trusted is covered under are bubble balancers accurate, and whether home-mounted tires need balancing at all under do you need to balance tires after mounting.

Typical mistakes

• Skipping the leveling. A stand that is not level shows a tilt that has nothing to do with the wheel.
• Leaving old weights on. The Ranger manual and the manual of a Coats shop balancer both start by removing existing weights.
• A dirty center hole. The wheel centers on the cone by this hole. Dirt there shifts the wheel off its axis.
• Reading too early. Let the wheel settle to a stop first.
• Putting the weight on the low side. The weight goes on the light side, the side closest to the bubble.

Care of the balancer

The Ranger manual asks for little: keep the pivot pin in the upper end of the support shaft lubricated with 10 weight oil or an equivalent, keep the guide posts and springs free of dirt and lightly lubricated, and keep the head free of dirt and foreign material. For a balancer of another make, follow its own instructions.

A balancer to practice on

The steps on this page come from the Ranger manual, not from this product. Where the two differ, the instructions in the box of the balancer you bought apply. All tools for the rest of the job are sorted on the manual tire changer homepage.