So I see the Ronal/Firehawks are all 0mm offset, and the 17" GTAs are all 12mm offset. Why the difference? Is it just a random difference, or is it on purpose. Since Hawk's brought 'em to market, I figured they were to their specs, so it was probably on purpose.

I know the GTAs are 9" vs. 9.5" for the F'Hawks, and I haven't done the EXACT math, but I just figured 0mm all around was pretty much the accepted thirdgen aftermarket offset, without running a mismatched set like stock.

 

12mm is essentially 1/2" inch, and the wheels are different widths, so I would think that is the difference. I think they send one of them with spacers though? I can't remember if I got spacers with the crosslace wheels or not
I have the 17" wheels and I have some real Ronal wheels, so I could measure those and let you know. Ronals are on the car and the 17" Hawks are in the bedroom upstairs.

 

Nah, no need to measure, I was just curious. Hawk's "suggests" .25" spacers up front with the F'Hawks, and they said they include front spacers with the GTAs, but didn't specify size.

I've been talking to Mark at 6LE about wheel sizes and offsets as he gets set up to make a run of those new wheels. I was just curious as to what sizes all these various wheels are.

 

Hawks are 17x9 too. IIRC, The spacer is for use with standard 10.5" brakes.

 

On their website, it states the Firehawks are 17x9.5

 

That's total wheel width, just like GMs wheels are 17x9.5 but for tire measurement it's 17x9

 

I see. So technically, the GTA replicas are 8.5" in width for tire measurements?

 

The Ronals came with concentric 1/4" wheel spacers too, and it was to clear the tie rod end. The inside edge of the rim on the Ronal is square, unlike a traditional wheel, so it would hit the TRE. I would imagine the Hawks replicas are similar. Funny thing, I offered Hawks to borrow my concentric spacer so they could replicate them exactly instead of the cheapoo ones they offer with the wheels, but they only wanted it if they could keep it. Didn't make any sense to me.

 

Don't think so. Typos, wrong info are very common on the interwebs

 

Typin quick from my phone... my understanding was that width measurement was the actual rim, but that didnt account for .25" lip on each side. This was a given. Are FHawks the only wheel that acounts for the lip too? .....or are the new GTAs actually 8.5" +.5" for lip? Ive just never seen it written that way.5

 

I can measure them

 

9.5" is the mounting width, the actual width is more in the 10.5" range. What is stamped on wheels is the measurement that the DOT approves and has to follow certain rules. Most wheels (from outside of flange to the other flange are in the 1" larger than stamped range - although some truck wheels can be closer to 2".

Ronals have the BS they do to make the Brembo kit (optional on the Firehawk) fit flush up front - using stock brakes and even some aftermarket you need the spacers.

The 17" GTA wheels are not meant to fit 3rd gens - they are more of a "universal fit" - they fit 2nd gens, late g-bodies and many other GM cars. 9" is narrow - but some of those cars cannot fit a 9.5", so they chose 9".

When one says 0mm - it means nothing, just that the wheel mounting flange is exactly in the middle of the wheel barrel. When you say 5.25" BS on a 9.5" wheel (which also happens to be 0mm), it tells you a lot more.

 

BAM! -now that's learning something.

 

The wheel mounting face to inner-facing innermost wheel surface measure you favor calling "back spacing" is problematic in communicating how a wheel will fit effectively.

Your hypothetical thick-lipped truck wheel with 5" back spacing and a thinner lipped steelie with 5" "backspacing" could have 5/8" difference in where the bead sits. That means the tire could be placed in vastly different places, and that's enough to make a wheel that should fit be a no-go.

0mm offset means the wheel mounting face is in the middle of the bead surfaces, if the wheel is properly made. A decorative outside lip differing in thickness from a functional inner lip won't change that.

Now, there are advertised wheel backspacings listed for product, but a given offset wheel should put the tire in the same place as another wheel of the same offset, all else being equal. The backspacing measurement you subscribe to does not have that consistency.

And that, when people are of the mentality they have to use every last bit of space, is a problem.



As for bigger GTA wheels, 18s are the way to go and nearly available.

 

It is merely a measurement - there are many more factors involved that determine if a wheel fits or not: brake clearance, shape of the wheel well, suspension parts, etc. Now there is a range of what wheel sizes, wheel width, tire diameter, and tire width that will fit a particular vehicle.

Yes, certainly could be the case. In the case of a 3rd gen, almost every wheel - stock or aftermarket has an actual width around 1" wider than advertised wheel width. So if one has a slightly thicker lip, the bead might be off but the tire should sit in the same place relative.

While I haven't heard of BS advertisements being off from reality - it could happen. 5" of BS is more of an absolute than say 0mm offset would be. Honestly, you are losing me on this.

Depends on what you want to stick in a particular wheel well. For example, you need to tuck the wheel barrel right next to the tie rods with a 17" wheel to run a 275 tire, yet on 18" and larger you don't have that issue. Some older cars can barely fit a 255 up front with perfect BS and even some minor clearancing.

I hope those g-body wheels have the right pad height - Hawks dropped the ball by using stock pad height making even 4 piston calipers a clearance problem.

 

Ok, apparently, my memory is seriously slipping and in this case, I'm part of the wrong info on the interwebs.
I just measured my 1991 firehawk wheels. total width is 10 1/8th inches. Bead area is a bit larger than 9.5 inches.
Sorry for the wrong info earlier. I'm going to go on a wheel measuring spree for a refresher.