20 inch rotor alloys question

[glenandem]

looking at possibly upgrading to some 20 inch rotors and wondered are the reps different to the genuine audi rims, some look like the 5 spokes curl outwards abit more like theyre almost dished as opposed to others that look fairly flat?
is it just me or is there 2 different style rims?

[SJ250]

The reps aren't usually as concave as the OEM wheels. There is 1 brand that has a lot of dish but the name escapes me right now. In general though the factory ones are nicer.

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[glenandem]

thanks for reply, yes the concave style look much better!

[dieselquattro]

This blog has the different styles of the Audi Rotor wheels:

http://nickscarblog.com/reviews/audi...s-mega-gallery

[sferraro]

It's not so much the brand but what offsets each brand offers. I know Hartmann offers different offsets in a rotor rep for either a deeper or flatter concavity depending on your vehicle application. Check them out - the lower the et/offset, the more concavity.

[Skyler@Achtuning]

I know Hartmann offers different offsets in a rotor rep for either a deeper or flatter concavity depending on your vehicle application. Check them out - the lower the et/offset, the more concavity.

This is a common misconception actually, the Hartmann rotor concavity differs but only as a result of the diameter selected, the offset change only affects the back of the wheel.
The 18x8.0" version has around 35mm of concavity, much more than the OEM A3 rotor wheels do, the 19x8.5" version has around 35mm of concavity, about the same as the OEM S4 8.5" rotors but less than the OEM S5 9.0" rotor wheels, the 20x9.0" version has around 40mm of concavity, about the same as the OEM A6 rotor wheels but less than the ~60mm of the RS5 version.

[sferraro]

This is a common misconception actually, the Hartmann rotor concavity differs but only as a result of the diameter selected, the offset change only affects the back of the wheel.
The 18x8.0" version has around 35mm of concavity, much more than the OEM A3 rotor wheels do, the 19x8.5" version has around 35mm of concavity, about the same as the OEM S4 8.5" rotors but less than the OEM S5 9.0" rotor wheels, the 20x9.0" version has around 40mm of concavity, about the same as the OEM A6 rotor wheels but less than the ~60mm of the RS5 version.

Your post really doesn't do much to help clear up any of the original poster's confusion. Factoring in different diameters and widths and comparing concavities is like comparing apples to oranges. Also, an OEM 20x9 RS5 rotor has an offset of 26mm, not 60mm. An OEM 19x8.5 rotor found on A4s and S4s have 43mm of offset, not 35mm.

The original poster was asking about 20" rotor reps and different concavities. I told him to check out Hartmann. They offer two 20" rotor reps, both 9" wide. One has a 40mm offset and one has a 29mm offset. The 29mm offset (lower number) has a greater dish or concavity while the 40mm offset would feature a flatter face.

The OP should also know that offset will affect how far in or out a wheel sits in relation to the hub. Without knowing the vehicle, certain offsets may or may not work for a specific vehicle.

[Skyler@Achtuning]

I think you're confusing concavity with offset, offset is the measurement in millimeters between the exact centerline of the wheel and where the mounting face to the hub is located. On Audis the lower this number is the further out the wheel face is placed from the hub. The concavity is the measurement from the outer lip of the wheel to a point where the spokes angle in towards, typically the centercap. Perhaps if I place the information into a different format it will be a little clearer.

The Hartmann HTT-256 18x8.0" is available in an offset of ET32 or ET47 and has a concavity of 30mm in either offset. (I accidentally typed 35mm above)
The OEM Audi A3 rotors are 18x7.5" with an ET54 offset and about 15mm of concavity.

The Hartmann HTT-256 19x8.5" is available in an offset of ET25, ET38 or ET47 and has a concavity of 35mm in all offsets.
The OEM Audi S4 rotors are 19x8.5" with an ET43 offset and about 35mm of concavity.
The OEM Audi S5 rotors are 19x9.0" with an ET33 offset and about 55mm of concavity.
The OEM Audi TTRS rotors are 19x9.0" with an ET52 offset and much less concave than the S5 rotors though I have not measured or seen a set recently to take a guess.

The Hartmann HTT-256 20x9.0" is available in an offset of ET29 or ET40 and has a concavity of 40mm in either offset.
The OEM Audi A6 rotors are 20x8.5" with an ET45 offset and about 40mm of concavity.
The OEM Audi RS5 rotors are 20x9.0" with an ET26 offset and 62mm of concavity.

[sferraro]

I don't think I am. A lower offset should naturally increase concavity, at least on the same wheel design in the same width, right?. If the Hartmann 20x9 et29 rotor has the same concavity measurement as the Hartmann 20x9 et40 rotor, then the hub thickness must be different in each wheel, no? Otherwise, where do you make up the space to achieve the same concavity measurement?

[Turbavanttro]

I think you're confusing concavity with offset, offset is the measurement in millimeters between the exact centerline of the wheel and where the mounting face to the hub is located. On Audis the lower this number is the further out the wheel face is placed from the hub. The concavity is the measurement from the outer lip of the wheel to a point where the spokes angle in towards, typically the centercap. Perhaps if I place the information into a different format it will be a little clearer.

Skylar, concavity is not a measurement that any wheel manufacturers advertise or state as it is not as useful as width/offset. Concavity is just an aesthetic that results from the effects of offset versus wheel width, as sferraro correctly explained to OP. It's pretty clear that he wasn't confusing anything at all. Not saying concavity can't be measured, but not in the way you suggested. Most wheels with a concavity profile do not even have a uniform angle that the spokes angle in toward the hub, so you cant just arbitrarily choose a "point where the spokes angle in toward the centercap". This is why the standard measurements are width and offset. Manufacturers don't supply concavity data anyway so it's not useful for comparing one wheel design to another.

[sferraro]

It took a few fellow allroad friends to help me understand via the use of spacers, which makes total sense. I just wasn't picturing Hartmann using various hub widths across the same wheel design to accommodate for the same concavity measurement/profile. I was assuming the wheels used the same hub thickness across different offsets. Sorry for the thread jack - was only trying to help.

[Skyler@Achtuning]

No worries, just wanted to share some information. To clarify, yes, the Hartmann wheels offset change is similar to how a spacer changes the offset, the thickness of the back of the wheel is changed. As for how I measured, I put a straightedge across the face of the wheel and measured the distance between that and the centercap edge. This morning I had a chance to measure an OEM 19x9.0" ET33 S5 rotor which showed 64mm of concavity.