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I've got a set of 18" HREs that I use on the F40 sometimes.
 

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I have seen F40s fitted with both OZ and Enkei wheels. What are the pros and cons of each ? If I do go ahead and fit larger brakes, I will need to change the wheels as well.

May I ask, why on Earth would you want to fiddle with this car? What exactly are you expecting from it? It is, after all, a 20 year old design. Not only is the design 20y.o., the car isn't much younger, meaning that all of the suspension components are older, and the added stress of larger, more powerful brakes will accellerate wear and tear on the ball joints, control arm bushings, tie-rods, and wheels bearings.

Besides the bigger brakes, lower profile tires don't always equate to better handling. Sure, they will certainly give you a more responsive feel, but they can sometimes give you less grip. The suspension was tuned to tires with a certain amount of sidewall roll, mainly the static camber settings and the camber rise geometry, and to less effect, the caster geometry.

If more stopping power is your ultimate goal, there is one alternative to larger brakes. EBC or Dunlopad, and maybe others, can make custom brake pads for you. Someone may already offer modern pads for the F40, although I doubt it. Modern sintered brake pad material is lightyears beyond the OE pads fitted to the F40. Although the cost of custom pads will be astronomical in comparison to production pads, they will still be a fair amount cheaper than a big brake kit, and will have a friction co-efficient of at least twice that of the 80's OE pads, which is good for about a 15-25% in stopping power, and will give you a more aggressive feel at the pedal. This would allow you to keep the OE wheels.

In the end, fitting larger brakes is easy enough to return OE equipment, so there is not much harm in trying them out, and you can always replace worn suspension components, I'm pretty sure there are alot of F40 parts out there somewhere.

As far as pros and cons of wheels go, wheels are wheels. If they are heavier than stock, rebound will suffer, if they are lighter, rebound will improve, which improves traction and stability over bumpy and uneven surfaces at speed. The offset is of some importance also. If they increase trackwidth, even just a little, the suspension settings will feel softer, due to the added leverage against the suspension components and visa-versa for less offset.

I hope I have been of some help to you Boxer, and I hope that those two wonderful supercars you own havn't jaded you too much!:rofl: Maybe upgrading to an Enzo will satisfy your performance desires, sheesh:rolleyes: just kidding!
 

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As far as pros and cons of wheels go, wheels are wheels. If they are heavier than stock, rebound will suffer, if they are lighter, rebound will improve, which improves traction and stability over bumpy and uneven surfaces at speed. The offset is of some importance also. If they increase trackwidth, even just a little, the suspension settings will feel softer, due to the added leverage against the suspension components and visa-versa for less offset.
No offense, but "wheels aren't just wheels". They are one of the most complex and most under regulated and inspected componets on a car. There are countless threads on tires and oil on every forum, but most look at wheels as fashion accessories.

Here in the US, the industry regulation is a joke and most of what you see on the road is imported from China and made from recycled aluminum or a price point driven alloy, not a performance driven design. Also, there are very few brands who produce their own, and even those that do often don't use the best methods, materials, engineering or finishing processes. Here are some things to keep in mind when choosing a brand. I'll refrain from offering my personal opinions (or inside company knowledge) on specific brands, so if you want details on something specific, feel free to PM me direct.

Materials:
Aluminum is lightweight but tends to bend easily, so you mix in alloys to add strength. Only 1 brand mixes their own, most buy on the commodities market what's available and what's cheaper at the time.

Magnessium is lighter but very prone to hairline cracks. It's corrodes easily with atmosphere and UV light so wheels need to be constantly checked for chipped paint and touched up. It's usually 2x's + the price of aluminum so it's rarely seen in street wheels (Porsche Carrera GT uses a forged magnessium wheel that is $7k cost per wheel).

Carbon: used extensively in street bikes, just recently offered for street cars by Dymag (Koenigsegg is first production car to use), sometimes uses an alloy spoke, sometimes a carbon/kevlar weave. 1/2+ the weight of aluminum and magnessium and better impact properties. As use increases and production costs go down, it will be the best option for most performance applications.

Types:
1 piece: entire wheel is formed from 1 piece, meaning offset is fixed. Usually cast.
2 piece: outer barrel with a seperate inner face. Offset is usually set (sometimes adjustable by using different spokes shapes), allows you to swap out spoke designs or mounting patterns.
3 piece: barrel is made up of an inner, outer, and by mixing and matching, you can create custom offsets easily and them mount a center section for different spoke patterns and mounting patterns.

Process:
Cast: weakest and most inexpensive method. More porous product so you need a heavier and thicker design to make product strong. Typically seen on factory cars. Usually a 1 piece design, can be elaborate since it's a casting, occassionally it makes it way into a multipiece design.

Flow formed cast: large steel rollers press and stretch the outer rim of a heated cast wheel to compress material and give properties similar to forged product. Also uses only 4" of material to make a 6" wide wheel (less rotating mass)

Die Forged: Multiple pressings control the grain structure to allign down the spoke, curve with the bend and follow the radius of the outer barrel. Most expensive of processes however the strongest, lightest and most consistent as all pieces are forged into product.

Rotary Forged: The material is rotated under pressure and this forces the material out into a disc. The structure of the material is not as uniform as die-forging, entire product has a circular grain structure (weak spokes). Although this is considered a forging process, it does not use the extreme amount of pressure that is used in die-forging

Solid Forged: The initial forging is produced from a single tool. The rim is spun and then it is ready to have the design machined into the solid center. They can produce many different designs and bolt circles from a single tool.

Semi-Solid Forged: Combination of casting and solid forging process

Things to consider:
-US DOT stamp is a joke.
-German TUV should be minimum requirement for your consideration
-Japanese JUL is a little more strict, but it's a small market so not all brands submit for certification
-Some brands "build to your specs", that means alot of stacked tollerances which can lead to a wheel that isn't necessarily round, or one where the center bolts aren't properly centered.
-Load ratings are important. yes, a wheel may bolt up to your car and clear brakes, but if the load rating isn't accurate, you could have a major failure
-Magnessium wheel age. A deal on a set of race wheels is rarely a good deal
-Air corrodes. A quality wheel will have the inner barrel (inside the tire) painted and sealed to prevent this.
-When possible, use Nitrogen in tires (more stable, holds consistent pressure longer, removes moisture from air and less corrosion)
-Wheels can rarely be repaired. The heating and stretching process changes the grain structure. You're effecting roundness, weight (balance) and strength of the wheel
-DON'T POWDERCOAT!!! Powdercoating heat cycles a wheel, and usually need 2-3 attempts to get consistent finish. Each thorough heatcycle (track use and brake temp flashes don't heat through) can reduce the structural integrity by as much as 30% each time
Trust OEM. If someone isn't using it as OEM on their car, I'd be very hesistant to trust it. Yes, OEM designs are a compromise in performance and cost, however OEM's are scared of lawsuites and insist in quality and capable products. If no one is trusting a brand for OE use, I wouldn't use one of their aftermarket products.

Since you asked about 2 specific brands.

OZ is currently controlled mostly by Tirerack, if buying a product for your car, be sure to research exactly where it was made as all items aren't still made in Italy as they once were. Overall a quality and consistent product. Used by OEM in some applications as well as spec for some racing.

Enkei is usually used in cheaper Japanese applications but have recenlty seen a few high end cars using it. Some Japanese OEM applications, consistent and quality product, I'd check load ratings on specific model before using on the track or for heavy driving.

Hope this helps

Ron
 

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Thank you Ron for that on rims. It was a very informative post, and definitely educates on the differences in rims.

Chris
 
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