Speedline Challenge Wheels Buyer’s Guide (SL886)

The Speedline “Challenge” wheels (part number SL886) were available from Speedline through Ferrari and were intended for use on 355 Challenge Series race cars, but have become a popular upgrade to road cars. This is a guide for those wishing to purchase a set.

Later adopted to some 348 Challenge cars sometime in 1995 during the 348/355 overlap – earlier races used the standard 17” road car wheels — and fit to the 355 Challenge cars from the outset, these magnesium wheels are a popular upgrade for 348 and 355 owners alike due to their light weight, clean aesthetics, and motorsport provenance.

For 348 owners in particular, the dwindling availability of 17” tires and the relative bulk of the car’s standard aluminum wheels make these vintage Speedlines an especially desirable upgrade. (Note: standard 355 wheels are also magnesium)

Sizes and Specs

The correct size and spec for the 348/55 chassis is as follows:

• Front 18” x 8” et49
• Rear 18” x 10” et68

Other sizes are believed to exist with slightly different faces, but they have not been adequately documented and are not part of this guide as of yet. Early versions of the wheel are believed to have been produced in very limited numbers in both 5 lug and center-lock configurations for Michelotto for its 11 GT Competizione cars.

It is recommended buyers stick with the specs above. Variations in the above could also be indicative of fakes/replicas. Look for the markings below to insure you have a genuine set.

Weight

Weights should be roughly as below.

Restoration

Being magnesium, proper restoration of the SL886 should be handled by a professional used to working with the substrate. Treating a mag wheel as you would an aluminum or steel wheel will result in poor results at best, and a conflagration at worst. To get a proper smooth factory finish these wheels need to be carefully stripped and then painted, not powder coated. Powder coating mag wheels is likely safe, but a bit controversial due to the temperatures involved and the poor resulting finish. Expect to pay significantly more to have a mag wheel refinished than you would a “regular” wheel.

Decals

Several different decals appeared on the spokes of the SL886 over the years; the three below are considered correct. Anything else is a poor recreation.

Fitment

For some owners the fitment of the SL886 can be less than desirable aesthetically. Below are pictures of standard fitments as well as those augmented with spacers.

Credits

Special thanks to “ShineKen” on FerraiChat and this FC thread where most of the info for the post was derived.