Trailer Technical Details from McGill Manufacturing

When finishing your The Roadster Trailer you may find this information useful. The high quality of the gel coat will make painting your trailer easier and selecting the right taillights and wheels to match your car, complete a look that's sure to turn heads at cruise nights and car shows.

Several suppliers offer street rod taillights that will work with The Roadster Trailer. Early Ford teardrop or Zephyr taillights look great and are also available in L.E.D. models.

Custom wheels properly fitted to The Roadster Trailer can really be the finishing touch. To begin, you can review the info on on backspacing, offset and tire selection below to assist in getting the best fit.

Torsion Axles

Torsion axles used in building The Roadster Trailer eliminate the need for heavy leaf springs used with a tubular axle and provide a smoother ride.
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The construction of torsion axles utilizes rubber cords surrounding the inner bar. The wheel is attached to a trailing arm which is in turn attached to the inner bar. When you hit a bump the trailing arm causes the inner bar to twist against the rubber cords dampening the effect. For a smoother riding trailer you can also reduce the air pressure in your trailer tires. .
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Measuring Bolt Patterns

The standard bolt pattern on The Roadster Trailer is 5 on 4 1/2, meaning 5 lugs on 4 1/2 inch centers. This is the normal configuration for Ford wheels. Torsion axles with a Chevy bolt pattern of 5 on 4 3/4 is available for an additional fee. If you want to use wheels that have a different pattern please check with us when ordering.

When tightening your lugnuts, follow the staggered sequence illustrated below.

LUGNUT TIGHTENING SEQUENCES

Note: It's a good idea to tighten the lugnuts on new wheels again after driving about 50 miles. There may be a some settling as they seat themselves.

ROADSTER WITH TORQ THRUST II WHEELS

Wheel Backspacing

Backspacing Definition

Backspacing is the distance from the inside lip of the wheel to the surface that bolts up to the axle. See Backspacing Illustration.

WHEEL BACKSPACING DIAGRAM

Standard Backspacing

The Roadster ships with basic bias ply trailer wheels which most customers replace to match their car. A wheel with a 3 1/2 inch backspace will generally fit nicely inside the fenders of the Roadster.

MEASURING WHEEL BACKSPACING The easiest way to measure backspace is to lay the wheel face down onto the ground so the backside of the wheel is facing up. Take a straight edge and lay it diagonally across the inboard flange of the wheel. Take a tape measure and measure the distance from where the straight edge contacts the inboard flange to the hub mounting pad of the wheel. This measurement is backspace.

Caution: Reduced backspacing increases the load on bearings and may put the outer edge of your tires in contact with the outside of the fender.

Wheel Offset

To determine the wheel offset, you'll need the following measurements..

Wheel backspace
Wheel Width
Wheel Center line (outboard flange to inboard flange measurement / 2)

Subtract the wheel center line from wheel backspace to get offset. If backspace is less than the wheel centerline the offset is negative. If backspace is greater than the wheel centerline the offset is positive.

To convert from inches to mm multiply by 25.4 To convert from mm to inches divide by 25.4.

FINISHED ROADSTER TRAILER

Tire Width Equivalency Table

You may also find the following table of recommended tire widths for given rim widths useful when changing your tire width. This is just a basic guideline, always check with your tire technician when making your selection.

Rim width	Min tire width	Ideal tire width	Max tire width
5.0 inches	155 mm	165 or 175 mm	185 mm
5.5 inches	165 mm	175 or 185 mm	195 mm
6.0 inches	175 mm	185 or 195 mm	205 mm
6.5 inches	185 mm	195 or 205 mm	215 mm
7.0 inches	195 mm	205 or 215 mm	225 mm
7.5 inches	205 mm	215 or 225 mm	235 mm
8.0 inches	215 mm	225 or 235 mm	245 mm
8.5 inches	225 mm	235 or 245 mm	255 mm
9.0 inches	235 mm	245 or 255 mm	265 mm
9.5 inches	245 mm	255 or 265 mm	275 mm
10.0 inches	255 mm	265 or 275 mm	285 mm
10.5 inches	265 mm	275 or 285 mm	295 mm
11.0 inches	275 mm	285 or 295 mm	305 mm
11.5 inches	285 mm	295 or 305 mm	315 mm
12.0 inches	295 mm	305 or 315 mm	325 mm
12.5 inches	305 mm	315 or 325 mm	335 mm

Suggestions for interior finish

There are several things you might do when finishing the interior of your Roadster Trailer. You might choose to have it completely upholstered to match your car.
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If you plan to carry items such as tool boxes and spare tires, you might not want to carpet the sides or even the floor. One option is to paint the interior. You can even use Kilz primer to get a nice clean look that is easy to maintain. A combination of painted sides and a carpeted floor might be the way to go. Carpet can be glued down, secured with Velcro or snaps so it can be removed for easy cleaning.
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This information is only intended to give you a starting point to make choices on how to finish your Roadster Trailer and not intended to endorse any particular product or procedure.