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The Lotus Seven S4 (Type 60) was provided standard with 5 1 / 2 " x 13" pressed steel 'bolt-on’ wheels with chromium plated hub-caps ( [link] ). As an upgrade 5 1 / 2 " x 13" light alloy 'bolt-on' Brand Lotus rims were available at extra cost ( [link] ). Both wheels were supplied with either 165 x 13” Dunlop SP Sport or Goodyear G800 radial tires as standard.
Several of the tires on LBS4/2894/GT had burst as a result of fire damage, and all of the road wheels showed smoke damage ( [link] ). No physical damage appears to have occurred as a consequence of the fire; however, one of the wheels shows some indication of damage due to curbing. As a consequence of being mounted at the back of the car and hence the furthest from the fire, the spare wheel showed only limited damage other than that expected for a wheel of its age ( [link] ).
Each wheel was initially media blasted to clean of all the paint and fire damage in order to determine whether any structural damage occurred; however, the wheels appear suitable to use for street applications.
The wheels were cleaned, polished, painted, and clear coated by Wheel Wizard ( www.wheelwizard.com ) in order to return them to the original style ( [link] ). One of the finished wheels is shown in [link] and [link] .
The original lug nuts were damaged by age and possibly the fire. The stud has a right hand pitch of 7 / 16 ” x 20 and replacement items are available from Redline Components, Ltd ( [link] ).
The original size tires were 165/70 x 13”. Unfortunately, in the US this size is not as readily obtained, and so an alternative size was chosen. However, it is important when choosing alternative tire sizes that the overall rolling diameter is kept as consistent so that the speedometer reads correctly. A useful tool for choosing alternative tire sizes is provided on the www.Miata.net web site. It allows for the calculation of diameter, circumference, and speedometer correction when comparing two different sizes of tire. [link] shows the comparison of the original size and potential sizes of available tires.
Specification | Sidewall (in) | Diameter (in) | Circumference (in) | Difference (%) |
---|---|---|---|---|
165/70-13 | 4.5 | 22.1 | 69.4 | n/a |
175/65-13 | 4.5 | 22.0 | 69.0 | +0.6 |
175/70-13 | 4.8 | 22.6 | 71.1 | -2.5 |
Based upon this program it was decided to use the 175/70-13. Tire Rack ( www.tirerack.com ) stocked a small selection of this size including the Kumho Solus KE21 ( [link] ) and 722 ( [link] ), the Michelin Defender ( [link] ), and the Sumitomo HTR T4 ( [link] ).
Since all the tires available have a similar tread pattern, and the tires will simply be used for storage during the restoration and for initial testing, it was decided to use a set of Sumitomo HTR T4. [link] shows a view of one of the tires mounted on the restored wheel.
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