chriswd62

Thanks, but it's Guards Red. It does look orange in certain light.

I believe the rules state the +1"/-1" wheel change is available on the "standard part". It does not say anything about the entire set being used together, so I could purchase the car with a set of 19x8/10s and a set of 20x8.5/10.5s from the factory. Assuming I had both sets in my garage, I could use the 20x8.5s (or 19x8.5 with the -1" rule) in the front and put the 19x10's in the rear if I chose to do so, even though they are different styles. They should all be considered "standard parts".

PedalFaster

Your interpretation of the rule is incorrect -- Lehman is right. From the preamble to the Street rules:

(Emphasis mine.)

Based on what you wrote, you could not order a 718 delivered with 8.5" wheels on the front, and 10" wheels on the back, so running in that configuration wouldn't be legal.

chriswd62

Hmm. If that's correct, then that's a bummer. I'd hate to have to spend another $3K for two new .5" wider rear wheels just to meet this interpretation of the rules, even though it would be in my favor from a performance prospective. I'd hate to think that I could be protested for running a wheel that is narrower that what the max option would be.

burglar

Unfortunately, if someone were to protest you, it would be upheld.

Oddly, you could legally run a 20x10.5 on the left rear, a 21x10.5 on the right rear, a19x8.5 on the left front and a 21x8.5 on the right front if that was your bag.

sjfehr

Yep, afraid so. And it's not just an internet interpretation, it's the rule. That would be a pretty weeny protest, though, protesting for too-small rear wheels.

User 52121

Scooby921

I can see it from a weight perspective. Using 10" and not 10.5" does save some tiny value in weight and inertia. If the margin of victory was 0.01 seconds I can see it being meaningful. If you win by 1 second and someone protests they are just an *******.

Jawnathin

Started to look up 981 Caymans and this is news to me. Thought it could only run a 8" front and 9.5" rear so this is awesome. In addition to the width benefit, the 8.5" front and 10" rears have so many more wheel options.

So with that in mind I started looking up wheels and nearly all of the rear offsets on the 19x10s from TR are not legal. I like the OZ wheels.

OE Rear - 10 x 20" ET50
OZ Rear - 19 x 20" ET40

My question is, is it possible to stack both the optional 5mm spacer (XRP) option AND the 7mm offset allowance so it could legally run the +40 wheel? I took a look at the rulebook and it says - "On vehicles supplied with an OE wheel spacer, the wheel spacer shall be considered as a part of the wheel."

So +50 wheel w/ spacer = OEM +45. And with the 7mm allowance; up to +38 = legal? Did I get that right or am I doing a bit of double dipping?

Jawnathin

Sorry for hijacking a thread on 718s with 981 questions but don't want to create a new thread for this. If preferred I can do that.

For the 981 - PASM vs X73. Any definitive conclusion as to which is better? I know X73 is 10mm lower and gets bigger bars but the loss of PASM shocks seems significant given how well they work. I am leaning towards PASM since it is easier to convert to X73 but if I am going to end up running X73 anyway then I'll consider starting there. It is also easier to find a PTV + X73 car than it is a PTV + PASM car.

Thanks.

sjfehr

You're allowed to go +/- 1" of diameter. What you should really be looking for is 8.5x19 & 10x19 because of tire availability. You may have to get some wheels custom-made, but Forgestar and Apex are both price-comparable to OZ and look just as good.

Jawnathin

Thanks Steve, I misquoted the wheel specs. I meant to say I like the 19x10" OZ wheels and I will certainly take advantage of the +/- 1" diameter allowance. The question I have is whether I can legally 'double dip' the offset allowance AND the 5mm spacer option to have a broader legal offset allowance.

Option Code XRP = 5mm spacers for all wheels
Rulebook says - "On vehicles supplied with an OE wheel spacer, the wheel spacer shall be considered as a part of the wheel."

The practical use case is...

OE rear = +50 (allowable offset = +43 to +57)
OE rear + XRP = +45 (allowable offset = +38 to +52)

So if allowed then the +40 of the OZ should be legal. I think the only catch is that if I claim that option code that it applies to the front too. However in the case of the OZ front wheel specs it still falls under that allowance.

OE front = +57 (allowable offset = +50 to +64)
OE front + XRP = +52 (allowable offset = +45 to +59)
OZ front = +53

Not sure if anyone has gone down this exercise before that could definitively answer. I can write a letter to request clarification but thought I'd check here first.


EDIT: I also need to verify it was possible to order the car with XRP. Can't find a 981 with them.

burglar

Not sure about the 981, but on the 987 it says in the Porsche literature explicitly that you are not allowed to combine XRR (the big wheels) and XRP (the spacers.)

Looks like it's the sport techno (XRT) option on the 981 that gets you the 8.5/10 (ET57/50) combo. I don't see an XRP option in the brochure. The Stuttcars site lists XRP as an option for a 981, but I can't find it anywhere else, and I also can't find a wheel spacer option on the current 718 build site.

There ARE spacers listed in the Tequipment catalog, but it says they are only for use with 18" wheels, which means they are no bueno for the big 20s.


So based on that, I would say you need to stick within SCCA tolerances of the original 20x8.5et57 / 20x10et50 to properly be able to defend a possible protest.

Scooby921

Yes, and the rear offset kills every off-the-shelf 19" option. Every off-the-shelf wheel I could find in my months of research is a 19x10 +40 rear. To go custom forged is $1000~$2000 per wheel. If you want to be legal to national rules and not get protested at national events you are forced to run OE wheels or spend the money on custom. I'm just out for fun these days, so I knowingly bought illegal wheels. If someone protests I'll admit fault and give up the trophy. If the results are close enough I'll probably give it up on my own as the extra width might be worth a couple tenths. Of course the 20lbs I would have saved running forged wheels and the extra 3" of tire I am missing by using OE sizes are probably worth more than a couple tenths on a fully prepared car.

Mport68

Actually, the protest would be for too large a front wheel... and IMO that's a legit complaint because although it's possible to stuff a 255 on an 8" wide wheel, it works much better on an 8.5" width

burglar

You can get a set of custom-spec Forgestars for the price of one fancy forged wheel. I hear the lead time is pretty long though.