348 SL886 Challenge Wheels / tyre genie replicas

I've been asked tonnes about both sets of these wheels so I thought I'd detail how they came to be in a thread here.

I've always loved the look of the magnesium challenge SL886 wheels, and bought a set from a member which I had refinished. However one still had a tiny crack, and it turned out when inspected further they're all slightly buckled and need straightening. I am pretty sure they did some hillclimbing and probably saw some action, and they don't even appear to be a matched set anyway. I got them fairly cheap as a bit of a risky project with all this in account, so I decided to pursue having a replica set made, in the meanwhile I could get around to having the mags fully repaired by a specialist. Here's the SL886 mags as they are:

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This is with 235/40 R18 P Zero fronts, and (very old) 265/40 R18 Trofeos on the rear. I saw a lot of debate (and a lot of people running tyres I considered much too big on these wheels) but to remove speculation I found someone who had the 348 manual and had posted the page (obviously ignoring slick sizes) - so proper ferrari/speedline tyre sizes are:

235/40 R18 front
265/40 R18 rear

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Using an online calculator, these sizes keep the overall radius closest to stock and therefore have the least effect on ride height and speedometer accuracy. They also don't have any scrubbing issues. 225/40 is also a lot more common than 235/40 and therefore much cheaper too.

Offsets I found after digging about:

bolt pattern 114.3 X 5
18 x 8 front 49mm offset
18 x 10 rear 78mm offset

So on to the replicas. I'm in the UK, but I found a listing on Australian ebay under 'tyregenie' - reasonably priced, the listing showed a pretty confusing set of images of clearly genuine Challenge SL886 wheels, plus a couple of different ones. I took the risk and after a bit of discussion with the vendor, ordered them, on the condition we could work towards getting them closer to the real thing. I'd seen people consider the listing before but not pushed the button, so consider me the guinea pig....

I knew they didn't have the exact original pattern and likely couldn't match it, but I went back and forth with them adjusting their design, sending measurements and overlaying photos of mine to get the most similar look possible. They sent back renders each time. They weren't able to curve the spokes out or match the varied spoke depth, and they use their own bolt length and centre cap diameter, so there are some variations with the dishing and thickness of the hub, but ultimately I think we arrived at a design that pays homage to the challenge wheel and looks period correct. I think perhaps it almost suits the 348 better - looking a bit more 80s chiselled. The quality and sharpness of manufacture is as you might expect, several times better than the 1990s mags.

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Haven't taken nice Fuji shots of the reps yet so excuse some iPhone snaps...

Here you can see the thickness and curvature differences, less apparent with the rears.

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I had the reps fitted with 225/40 / 264/40 Michelin PS4s, which although less dramatic looking than a Trofeo are an incredible tyre imo.

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Weights are
11.6kg rear 10.7kg front without tyres
24.8kg rear 20.8kg front with tyres

And here they are on the car:

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Cost was GBP2600-approx delivered, with bolts and centre caps. I think tyregenie have raised the price since I ordered, not sure if this due to costs for them rising, or to compensate for the many times I made them go back and make changes, or both

I'll update the thread with some DSLR shots when I get time to get out and get some.

 

sorry forgot to say - forged aluminium. Probably a couple kg a corner heavier than the mags (not had tyres off the mags yet to get accurate comparison)

 

Thanks for info - yeah they’re on wobble bolts, and went on just fine, although having read an article it seems that’s quite a jump. Is a 355 114.3? Looks like I was given wrong info to begin with (no excuse for not checking, I am a bit new to some of this), maybe challenge SL886 came in 114.3 and 108 depending on year? If they weren’t mounted currently it would explain why they felt buckled lol…

most of the shape difference comes from the SL886 using a much longer OEM bolt which creates that thicker hub and more convex spoke profile, but that wasn’t something I was able to get the manufacturer to accommodate, so yea more of a homage than a replica

 

ok so after a steadily building wave of paranoia I went out and measured and checked the packaging, and both the mags and new wheels are 108mm . I pasted the info earlier from some notes I had made at some point which I must’ve corrected when I ordered. Phew. Image Unavailable, Please Login