Ironman88

Just purchased a set of HRE 3-Piece wheels from the seller who was running them on a 997 C2S.

My car is also a C2S, however I want to confirm if the fit will be correct as the new wheels have differing widths and offsets from what I'm currently running.

HRE's are as follows:

F: 19 x 9 ET 53
R: 19 x 12 ET 67

Current wheels are factory Turbo (1):
F: 19 x 8 ET 56
R: 19 x 11 ET 51

He was running the following tire sizes at the time:

F: 235 / 35 19
R: 305 / 30 19

He conveyed that he had no issues with fitment or any clearance problems. He sent me photos of his car with the wheels in question on it (attached PDF's below), and the car looked good to me...

Interested to get an opinion on how I should anticipate this change will affect the:
A) Appearance of the car
B) The way the car handles

Thanks.

Petza914

Yep, you're good.

19x12 et68 is the spec on an OEM GT3 wheel like on my wife's car.

19x9 et 53 is the same offset as the normal 8.5" wide front wheels so at 1/2 wider it will be like running a 1/4" or 6mm spacer. Should be absolutely perfect.

I would up size the tires on those wheels though. A 305 on a 12" rear looks a little stretched. That what we have on both our 997s and I'm changing it at the next set. Go to the tire specs chart for the rubber you want to run and compare the rolling circumference ratio for the normal sizes yiu mentioned (235 and 305) and then select a 325 width rear and either a 245 or 255 width front that keeps that percentage the same. I did the math on this already for my next set of tires, but the paper is sitting on my desk and I'm not at home.

Shock Arrival

Those are going to look outstanding Ironman...can't wait to see them on your car!

Post em' up when you've got them mounted!

Ironman88

Thank you Pete. Helpful information.

The only question that is in my mind now is the width of the fronts (9" vs the more typical 8.5".) I am wondering how the additional width may impact handling. Also some concern about the appearance of the "poke" the fronts may have (very hard to ascertain with my car on the jack with the new front wheel mounted - with the suspension not being loaded, the wheel looks like it projects well beyond what I would like to see.) {Photos of that below}.

I do have the option of having new inner barrels made for the fronts - taking the overall width of the fronts to 8.5". The cost for that (via HRE) would be about $500. I'm contemplating doing that.

Regarding the chart you've mentioned above - where would I find that located?

Thanks again for your insight and advice.

Presto

it all comes down to tire sizes. if you want to run a 235 front tire, then you dont need anything more than a 8j up front. 245 tires 8.5j is ideal. For the rear 12j is quite wide for a 305 tire. 11.5j is best for 305, it wont look stretched. Ive seen people do 305 on a 11j and it kind of has a muffin top look which im personally not a fan. I wish companies made 8.5 and 11.5 wheel width combos for our cars.

Petza914

They do. I have a set of forged Champions for sale in exactly that width combo.

Petza914

Is that front all the way on and bolted over the hubcentric flange. It does look like it's further out than the specs show it should be, but it might just be because it's unweighted. From the specs, those fronts should tuck in just fine once loaded. If you think about the 19x8.5 wheel many people run and then add a 7mm spacer at the front for ideal fitment, that's essentially what these wheels you now have are less 1mm (further in). However, some 997s are not made evenly side to side - mine is one of them. My right side wheels project further out both front and rear than the left side wheels do. I did my offsets to be flush on the right side as I can't stand the poked look so my left side wheels actually look a little too far in than I'd like them to, but it is what it is. My wife's car is even on both sides. You may want to swap that front test wheel to the other front position and see if it looks the same or different as you may have one of those special 997s like I do. Supposedly, this is not uncommon.

Rears based on the GT3 wheel spec on my wife's car is also only different by 1mm - no big deal.

For the tire chart, you go to the tire manufacturer website for the specfic model of tire your want to run. I use Nitto Invos on 4 of my cars, so for reference,

https://www.nittotire.com/passenger-...formance-tire/

then you look up the tire sizes you're currently running, in this case, a
235/35-19 has a diameter of 25.35
and 305/30-19 has a diameter of 26.22
making a F/R ratio between those two 25.35/26.22 gives you a percentage difference of 0.97 or the fronts being 97% of the rears. You want to keep the F/R ratio within 3% to keep the ABS and PSM system happy.

Now, looking at new options, let's say you want to run a 325 width on the rear....
325/30-19 has a diameter of 26.77
multiplying this by the same 0.97 factor means you're looking for a front tire size with a diameter of about 25.97.

In this chart, there are two options
245/35-19 has a diameter of 25.79 so the ratio is 25.79 / 26.77 = 0.9633 or 96.33% or
255/30-19 which has a diameter of 26.1 and a ratio of 26.1 / 26.77 = 0.975 or 97.5%

The 245 tire is 3.67% different than the rear and the 255 tire is 2.5% different than the rear, so the 255 width tire is actually the better fit from a rolling circumference (diameter) perspective so that's what I'd go with, and now that I've redone the match here, what I will go with when it's tire time on the silver 997. Adding some additional front grip helps the handling of these cars that can push a little in the turns, especially the AWD ones (though I know yours isn't).

Different tire brands and models can have slightly different numbers so if you run Michelin PS4S or something, go to their website and do the same calculations.

If you don't want to go all the way to a 325, you can also probably find a 315 and then run the numbers again to see if there's a front size that falls within that 3% variation.

The only thing I had to do on my car when installing the wider 12" rear wheels was trim a notch out of the oversized GT2 rear brake air scoops I'm running to make a little clearance where the wheel runs.

Hope that helped.

Ironman88

That is a huge help Pete.

Many thanks.

GTS Sully

Pete is spot on with his input (again), and the tire size suggestion will be perfect, Ironman. I'm running 325 and 245 wide Michelin's on my GTS with the same wheel sizes, ironically from HRE.

arscottp

Your pictures on jackstands, with the suspension uncompressed, are making them look farther out than they'll actually be (because of camber gain).

You could put some 2x4s under the barrels and lower it onto them. That will give you a better idea. But, you shouldnt be worried, 19x9 +53 will fit well.

hexagone

These wheels will fit just fine. As noted above they're uncompressed, which makes them poke .5-1" beyond where they would actually sit.

Waste of money to get new barrels or even work through HRE - unless you have $ to blow.

Ironman88

Thanks for the reply GTS Sully.

What Michelin tire are you running? These maybe...?

https://www.tirerack.com/tires/tires...omCompare1=yes

Have you experienced any issues with tram-lining with the 9" fronts? Any other issues felt through the steering wheel?

I realize I am sounding overly cautious, but my plan is the have these wheels rebuilt and refinished - so there'll be an additional investment associated with that...

Thanks again.

Ironman88

Thanks Hexagone.

By the way - I've initiated some discussion with Dave @ Renewed Finishes about restoration of the HRE's. You had some influence on opening up that opportunity - appreciate that.

GTS Sully

Those are the exact tires I'm running. I've had zero issues and no negative feel at all with the steering wheel. Smooth as silk. Had a balancing problem initially but got that sorted out. You should be fine!

Ironman88

Circling back on this thread.
It's taken a few months, but the restoration work on the HRE C20 wheels has been completed. (The work was skillfully done by Dave Waltermeyer, Renewed Finishes - located in Pennsylvania.)

Photos shown below that illustrate the progression of steps through the process...



Original black matte finish centers. At this point I had already polished out the curb rash on them.

Some deeper pitting in the right rear rim. Quite a bit of work to remove it.

Rear rim ready for polishing

Full brushed centers - Dave's work is outstanding. He is an artist.

Brushed centers with bead-blasted bolt pockets.

The C20 wheel is from HRE's competition series. Very light weight. Titanium hardware connects the centers with the barrels and outer rims.


Ready to ship. Really happy with the results.