308 17" wheel design

I have been fooling around with a wheel design for the 308 series. I know the market for 308 wheels with the proper offset and the 5x108 PCD is very shallow and tends to be overly expensive.

I thought a wheel with the classic 70-80's style but updated with a modern touch and sizing would be welcomed by 308 owners. Allowing for more brake size and a better selection of tires.

I have drawn a 17x8 front, 17x9 rear set. Nothing about this wheel is finished. it is only a drawing board model currently. It has not been optimized for strength, weight, or manufacture at this time. The material is aluminum, and a forging would be preferred as it can reduce the section thickness due to greater strength, and thus save weight.
There is also the possibility to change to a 2 or 3 pc wheel design, where only the center needs to be manufactured, which is always better for short-run wheels.

As for design, I am showing 2 wheel centers. Give me some feedback if you like the modern or throwback style.

And before you ask, "can it be made?" the answer is hesitantly yes. But like all products, it must have a realistic business case before any manufacturer would touch it. And like everything in life, money talks and bull**** walks.

Let me know what you think of it so far.

Cheers
Eric
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Thanks, but I am not going to be making them. Its just a doodle for me. If somebody wants to take it and run with it, then I can finish it as a production ready part. For now its just a open forum subject.

I was trying to get a little bit of the old style campagnolos like on early boxers and Daytonas, but its hard to translate into 17" rims. The model has elements that are very specific to Ferrari wheels from the70-80's, I dont know of anything out there currently that looks like this. Current trends are toward split spoke type and very rounded and soft shapes.

The 16" QV wheel does look correct on the 308. But I wouldnt want to just build a replica. There must be more interesting possibilities than that.

Keep the feedback coming.

Cheers
Eric

 

Ok, for the first sets of rims i did, the spokes had an outboard curve, with a falling inboard recess in each spoke. Done for style really, it helps give a "deeper" look to each spoke, and some interesting surfaces.

Just to illustrate, i show a cross section of the first designs. see attached...

however, because it was asked for...next will be a 17' replica-ish version.

Cheers
Eric
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Ok, so now i have modified it to be a replica (best i can do without a QV 16 wheel here with me) rendered in a 17" size.

The spokes are flat as kansas, and the archiecture is similar to the 308 qv style.

Cheers
Eric
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Hold on a minute now, fact...? Are you assuming that 16 is a magic number at which there are no physical forces to fight?

the point is rotational inertia. not "gyroscopic" which infers angularity or a changing of rotational axis. There are small gyroscopic effects in turning, but they are minor compared to inertia issues, and are influenced by the same characteristics of the wheel/tire system.

The important factor is WHERE the weight is in the overall diameter of the wheel tire combo. How far the masses are from the axis of rotation. A 16 wheel and tire combo can be heavier due to the huge sidewalls of the tire compared to a short sidewall, lightweight aluminum section rim. Not always, but it is an example. aluminum is lighter than steel belt filled rubber. Thats fact.
The factors to consider are weight of the wheel tire combo, and the distances from axis. Until you have these weights to compare two tire and wheel combos, you are blowing hot air. Sportscar tires and wheels have been growing over the years for many reasons, all of them with technical merit, and the results in capability of modern vs. classic cars is unquestionable. The benefits in grip and performance of modern tires, coupled with the lower rotational inertial from more aluminum/less sidewall is well worth the effort to have a wheel capable of mounting modern tires for drivers who want to exploit the cars potential.

Larger diameter wheels, when done correctly have multiple performance benefits. When they are done simply to show off ("bling") they are hugely detrimental. We arent talking about "bling" here.

So if you want to keep your 308(s) museum pieces and dirve it to the level it was originally made to, thats great. But these sketches were done for fun to see what those who would like a wheel change would be interested in stylistically. Thats all.

Cheers
Eric

 

hey Birdman.

I agree that excessive addition in wheel width and weight can place extra strain on the axles and bearings. Heavier rims have a much larger impact on ride, turn-in, braking and acceleration. I am not talking about a heavier or larger rolling radius package.

IF the rolling diameter changes, (and adds weight at the outside diameter)then we are talking about possible problems with strain at the axle under hard acceleration.

also, the loads on the bearings/axles comes primarily from slip angle loading in a turn condition and moreso with power on. this is a simple G load calculation, the force at the axle will be applied with whatever size wheels.

---0.8 G load cornering is the same with 16 or 20 inch wheels -as long as the rolling radius is the same. the car doesnt care what wheels are there--

The 308 suspension and bearings are not anemic. If someone hasnt taken care of the car in the first place, they have no business putting loads on the suspension/bearings with whatever wheel.

These wheels are not some wild transformation. I am not talking about trying to win lemans with these wheels, or design something that the blinging hip-hop crowd would want. I say again, for those that prefer the 308 in a virgin form, and never want to load the suspension (heaven forbid!), then this topic is obviously not for you to begin with.

Also, I am not going to make these wheels. I am just fooling about with the design process. i have my hands full with OEM design projects at the moment.
But I get asked often enough to do this that I decided to give it a shot here to get some design input from car owners (the types who would modify them-haha)

by the way, the best way to not damage your CV's and bearings is to not drive the car in the first place. Once you decide to drive it, anything goes doesnt it?

Cheers
Eric

 

hey Birdman,

Sure, the wheels could be made. All wheels start as a drawing.

It could be done from a forged or cast aluminum "blank", of which I know many companies that make and finish them.
It could also be done as a 2 pc wheel, using exposed or hidden (ala HRE) hardware.
It could be finished and made by a wheel manufacturer, all they need is a PO for "x" number of wheels, and a warehouse to ship them to.

None of these options are cheap. And the lower the volume, the higher the cost. No way around that. - What price is too high for 308 guys?

The greatest issue, as always, is liability. I have not fine tuned the design for strength or durability using FEA. The radiuses and cross sectional thicknesses are all educated guesses currently. The process for finishing and testing the design for open market release is also very expensive. All of this could be done, but who pays for it? These costs overwhelm the potential to sell a handfull of them. - These reasons alone would keep me from building this wheel on my own.
The only option is if an existing wheel company took an interest in the design, and could internalize the costs and finish the proper tests to release it effectively.

So for now they are just a design exercise. The real world of liability and market size effectively crush alot of these types of products.

Cheers
Eric