This page is... UNDER CONSTRUCTION
WARNING: I am not an expert on cars, automotive engineering, VW Beetles, beach buggies or anything else discussed in these pages. What I have written is my current understanding of the issues involved in building Tina's buggy. These opinions are based only on my own research in books and on the web. They, therefore,have no basis in fact, may well be wrong and potentially downright dangerous if taken to be gospel truth. If you intend to use any of this information for any purpose other than pure entertainment, then please get its validity confirmed by someone who knows what they're talking about! You have been warned...
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The choice of wheels and tyres for a beach buggy seems to be a fundamental decision which needs to be made as early in the design and build process as possible, which I find rather surprising, as I had imagined it would be one of the last things to buy, along with the seats. This is because the choice of wheels and tyres are tied in with wheel arch clearance (both vertical and horizontal), suspension setup, brake efficiency and bias, gearbox and differential ratios and engine power requirements. A significant change in the wheel and tyre sizes could result in an almost complete redesign of the car!
The primary requirement for wheels is that they should be as light as possible. Light weight is required in order to keep the 'unsprung weight' of the car to an absolute minimum. Unsprung weight is made up of the tyre, wheel, brakes, hub, axle and suspension components. Increasing unsprung weight increases suspension momentum, which makes the shock absorbers work harder, makes it harder for the suspension to keep the wheel in contact with the ground and, therefore, adversely affects handling.
Wheels suitable for a buggy are available in both steel and aluminium in various sizes and styles.
Steel wheels are relatively cheap but are heavy compared to aluminium as they can weigh up to 3 times as much as an aluminium wheel of the same size. Corrosion can also be a problem as it can be difficult to maintain the condition of a paint or chrome finish in the UK climate.
Aluminium wheels are relatively light but are expensive compared to steel wheels. The finish on aluminium can be maintained to whatever standard is required by polishing and will not deteriorate beyond repair, no matter how neglected they are.
Before 1967, Beetle brake drums used 5 bolts in a 205mm pitch circle diameter (pcd) pattern to attach the wheels (above left), whereas, after 1967 they changed to a 4 bolt 130mm pcd pattern (above right).
The larger diameter 5 bolt pattern is much better than the 4 bolt pattern for off-road use, as it provides stronger mountings for the wheel, the wheel itself is stronger and the wheel is significantly lighter, giving improved unsprung weight.
Since I selected the 5 bolt pattern for my buggy and Tina's buggy is being made primarily of parts left over from building my buggy, Tina's buggy will also use the 5 bolt 205mm pcd pattern for her wheels.
Having chosen the 5 bolt pattern for Tina's wheels, this cuts down the number of available wheel options significantly.
Another requirement for Tina's wheels is that they are available in a range of widths from about 4 inches for the front wheels to 7 inches for the rear wheels, so that they will support fat tyres and fill the wheel arches reasonably. This requirement eliminates most of the aluminium alloy after-market wheels designed for early Beetles, as these are usually only available in sizes between 4 and 5 1/2 inches.
Available options for Tina's wheels are: steel 5 spoke buggy wheels, banded steel stock VW wheels, wrought aluminium race wheels or cast aluminium race wheels.
Steel 5 spoke buggy wheels are readily available in a wide range of sizes in either painted or chromed finish, althought the range of off-sets is limited.
Banded steel stock VW wheels give a classic buggy look, as these were popular in the 1970s, but they are only available second hand and so the range of sizes is limited.
Wrought aluminium race wheels are widely available from manufacturers like Centerline, CMS, Douglas and Erco in the US. They are very light, are available in a wide range of sizes, styles and off-sets and look good on a buggy but they are very expensive.
Recent developments in the US desert racing scene have lead to the development of cast aluminium race wheels from manufacturers like BTR Racing that are now comparable in strength to wrought aluminium wheels and these are not dissimilar in looks to the classic 1970s buggy slot-mag alloy wheels and would be well suited to a buggy. They are available in a limited range of sizes, styles and off-sets but they are the most likely sizes to fit a buggy and they are significantly cheaper than wrought aluminium wheels.
I will, therefore, use 4 inch BTR Racing wheels on the front and 7 inch BTR Racing wheels on the rear, of Tina's buggy.
Use the calculator below to suggest alternative tyre sizes with circumferences within a specified percentage of the original tyre size (Tyre 1). If the tyres under consideration are the ones driving the speedometer, then I suggest that the percentage difference in circumference is kept within 2.5%, unless the speedometer can be recalibrated easily.
The default sizes for Tyre 1 are for Rick's rear tyres.
Changes to the sizes for Tyre 1 are carried through to the calculators below.
Use the calculator below to determine the effect of changing your rim width and offset on inner and outer wheel arch clearances. First enter the wheel width and offset for Wheels 1 and 2, then click the calculate button. It will then show the difference in clearance between the inside of the wheel and the inner wing and how far the outside of the wheel edge will extend or retract. If you reduce the inner clearance too much or push the wheel out too far, the tire might rub or not fit at all.
Note: 1 inch = 25.4 mm