Technical Guidance for
Finishing your Roadster Trailer

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.


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.


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.


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.


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 BACKSPACINGThe 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.



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.


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.



The Roadster Trailer from McGill Manufacturing

Priced at $2,995.00, our Roadster Trailers are delivered in a gel coat finish with basic 14 inch wheels and tires. Each one has safety chains and a coupler for a 2 inch ball. The hatch cover has a keyed lock to protect your property.

This makes up the basic trailer kit that allows you to quickly finish out the trailer with lights and paint to match your ride.

Overall Length
99 inches
Box Length
68 inches
Overall Width
55 inches
Widest Box Width
45 inches
Between Wheelwells
33 inches
Overall Height
42 inches
Tallest Box Height
22 inches
approx. 450 lbs
Tongue Weight
Default Bolt Pattern ( Ford )
5 on 4 1/2
Chevy Bolt Pattern - Optional add $125
5 on 4 3/4
Solid paint one color
Teardrop tail lights (wired & installed)
Carpet floor and both sides
Carpet on floor only
Carpet on both sides only
Custom tubular bumper (painted)

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For more information, call us..

Phone: 417-472-7848
Fax: 417-472-3284

McGill Manufacturing
9945 Raccoon Road
Granby, MO 64844


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