RACING OFF ROAD ROCKCRAWLER BEADLocK AND NON BEADLocK  WHEELS  BY  MRW MANUFACTURERS OF "CUSTOM BUILT" MOTORSPORTS WHEELS SINCE 1955

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WHEEL OFFSET OR BACKSPACE

The the backspace (sometimes called offset) is the distance from the backside surface of the dished center  to the backside rim lip . ( technically the offset of a wheel is determined by measuring plus or minus from the center line of a rims width, this dimension changes for each rims width. So for simplicity MRW will use the tried and true backspace measuring method ). 

FIND YOUR WHEEL BACKSPACE OR OFFSET

IMPORTANT WHEEL MEASURING INFORMATION "click" to see more

The backspacing (sometimes called offset) is the distance from the inside surface of the dished center (B) to the inside rim lip (A).When you're ready to buy a new set of wheels, measure the backspacing  of the wheels that you know work - the ones on the vehicle. HOW TO MEASURE BACKSPACING FOR MRW WHEELS 1. Place your wheel (without tire) on a flat surface like a kitchen table or smooth level work bench with the valve stem up toward the ceiling. 2. Put a ruler down through the center hub hole. 3. With the ruler touching the table notice where the bottom side of the center touches the rule- That's what we call the wheel backspacing  . 4. If you plan to purchase a wheel with more or less backspacing or are changing to a different size or width wheel or tire take special care to make certain the inside diameter of the bell of the wheel clears  brake caliper (#3 diagram) or brake shoe, and also when you turn full left or right the tire or wheel will not rub the vehicles body, tie rods, struts, or other suspension parts at maximum spring compression or no compression.  WHEN ORDERING DOUBLE BEADLocK WHEELS "EXTREME CARE" MUST BE TAKEN ALSO TO CHECK FOR INTERFERENCE  OF THE BACK BEADLOCK WITH THE BRAKE CALIPERS, VEHICLES  BODY, TIE RODS, STRUTS, OR OTHER SUSPENSION PARTS
1. HUB 2. BRAKE ROTOR 3. BRAKE CALIPER 4. AXLE 5. STUD	G. VALLEY INSIDE DIAMETER H. BELL inside DIAMETER I. CENTER OF AXLE TO OUTSIDE EDGE OF CALIPER X. BACK BELL DEPTH Z. FRONT BELL DEPTH "	A. INSIDE RIM LIP B. DISHED CENTER C. INSIDE VALLEY EDGE D. CENTER WELD POINT E. OUTSIDE VALLEY EDGE F. OUTSIDE RIM LIP

PLEASE READ CAREFULLY BEFORE ORDERING  

The the backspace (sometimes called offset) is the distance from the inside surface of the dished center (B) to the inside rim lip (A). (technologically the offset of a wheel is determined by measuring plus or minus from the center line of a rims width, this dimension changes for each rims width. So for simplicity MRW will use the tried and true backspace measuring terminology). 

On a 15x8" wheel this backspace dimension can be anywhere from 1" to 5".    :-: Notice when measuring backspace,  (H) & the inside depth of the bell must clear the  brake calipers (3), and (A) and the bulge of the sidewall and the outside diameter of the tire clears the vehicles body and steering assembly when turned to the extreme left or right at full spring compression or zero weight (jacked up) no  compression .

The same holds true for 15x10" and 15X12" wheels because the only dimension that changes is the width of the 'valley.'

While it may appear that the backspace range should increase with the width of the valley, actually the critical dimension is the distance between the inside rim lip (A) and the inside valley edge (C). In the illustration at the top you will see that it is labeled (X) and has a dimension of 4". Regardless of the width of the wheel, X will always be 4" and Z will always be 1.5" in the case of MRW wheels. (There is an exception to this in our 'Wide Back Bell' shells. In this case X is increased to 5".)

MAXIMUM BACKSPACING

If (I) x2 (times 2) is greater than 12.625" (G) on a, obviously your maximum  must be just under 4". Otherwise the caliper will hit the valley of the wheel.

MINIMUM BACKSPACING

The minimum backspace is determined by the 'dish' of the center and the Back Bell Depth (X). While the typical center is 2-1/8" deep, part of that is the weld surface, leaving only a part of the actual center depth to work with. Also, the actual flat weldable part of the valley is shortened by the curve of the valley wall.

Placing the center at the extreme usable edge of the valley gives only a 3" backspace.

SO HOW DO WE GET LESS THAN 3" backspace?

By turning the wheel around and putting the Front Bell on the inside. This time when we put the center at the extreme weldable surface of the valley, we achieve and backspace of 1".

Normally, you don't need to worry about how we do it when you order wheels from us. We've been doing it a long time. We automatically orient the wheel to get the specified backspace. If it's from 1" to 5". However...

COMPLICATIONS

While we fabricated our shells (rims) and centers to exact specifications, the actual 'dish' and 'weld surface' of the centers can be different from the figures given here. For example, the dish of a Wide 5 bolt pattern is less than a 5 on 5 pattern. Some centers are only available in a flat configuration - with no dish at all! A flat center limits the  to 4-1/8"

Another complication is the matter of other support and steering members installed on the vehicle. It is possible to build a wheel that clears the hub and brake calipers but still won't work because it bangs into the steering assembly when the front wheels are turned. Not good.

YOUR BEST BET

When you're ready to buy a new set of wheels, measure the backspacing of the wheels that you know work - the ones on the car.

HOW TO MEASURE BACKSPACING

1. Place the wheel (without tire) on a flat surface with the outside up (hub side down).

2. Put a ruler down through the center hub hole.

3. note where the bottom side of the center plate strikes the ruler - That's the backspacing.

THERE IS NO SUCH THING AS A 'STANDARD' BACKSPACING! (OFFSET!)

There are too many variations between car and axle manufacturers. 2", 3",  4", and 5" backspacings  are popular and common, but not standard. We depend upon you to give us accurate backspacing  measurements. If you don't, you may have just purchased a very expensive set of paperweights or flower pots .

Many racing wheel makers buy their rims from people that make car rims, or farm equipment rims & when your tire falls off you lose the tire, many times the rim, and some times the car, and the race, plus you’re in the pits, & not on the track. That is what takes the fun out of racing. Don't plan on success or pleasure if you use cheap inferior  racing wheels  REMEMBER THE WISE OLD RACER SAYS "YOU MUST FIRST FINISH BEFORE YOU CAN FINISH FIRST"

MRW invented the BeadLocK for circle track racers in 1980 when competition was becoming so fierce that racers were literally tearing the tires off their cars. Since then MRW BEADLocK have become the standard by which other Type BEADLocK are judged

In 1976 M.R.W. Offered the industry's FIRST & ONLY Crash Guaranteed steel wheels. This was not only a commitment concerning our quality, but an opportunity for us to offer value to our customers when an unfortunate crash occurred. In turn it let us view and inspect tens of thousands of crashed wheels over the last 33 years, thrusting MRW ahead of the competition in the area of product improvement. This is all made possible by    YOU, THE  CUSTOMER

At M.R.W. we are so addicted to motorsport wheels, that we make over 10,000 different MOTORSPORT WHEELS

  ? what is motorsports ?

MRW MOTORSPORTS ACCESSORIES

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index two

 | 16# OUTLAW  wheels | STAGE II  wheels | STAGE III  wheels | ULTRA STAR  wheels | ECONO STAR  wheels |  RACING-BEADLocK - KITS  |RACING-BEADLocK -PARTS   ROCKCRAWLER  BEADLocK KITS  | ROCKCRAWLER  BEADLocK PARTS

MRW  ROCK CRAWLER WHEELS  15"  | 16"   | 16.5  |  17"  | 18"  | 20"

MRW  OFF ROAD WHEELS  15" |  16"  | 16.5" | 17"  |   18"  |  20"  | 22"

MRW motorsports ACCESSORIES 

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