I have no issue being proven wrong, you are the expert here, but if I'm wrong please let me know where. Is it the offset calculator that is incorrect?

 

I edited my post, hope it clears things up.
You can never think wheels alone, always add the tires. Think how a tire sits on a wheel, the outer edge of the tire is the issue, not the wheel.

And for the record, I am not an 'expert', I do not claim to be, simply like to talk wheels. It has been my passion from childhood.
But I am no engineer, I designed wheels and had other people to the technical work. But of course over the many years in the business I know a thing or two about it.

 

Yes, but as per the figures i produced from the offset calculator the wheel of the 12 /45 essentially sits 5mm out of the guard more than the 11.5/44. The tire and the wheel are partnered. Sure you can stretch the sidewall so the rolling diameter is reduced along with the sidewall clearance but essentially the extension of the wheel is greater using the 12 by 5mm.

Then there is the aspect of reducing the rolling diameter of the rear wheels to the front wheels once the rolling diameter of the rears are reduced due to the stretching. It is AWD don't forget and Porsche does state that replacing worn tires at one end is not desirable because the rolling diameter increases with new tires vs old tires at the other end. So isn't that creating the same scenario? Or should 9" be used in the front to counter the reduction in the rear? I know this wouldn't matter on a RWD GT3RS.

I don't understand. You would really need to explain it to me regarding the load you are referring to. If you are referring to the load being shared either side of the wheel bearing from offsets, most of these offset configurations we are talking about here are shifting between 6 and 11 mm's either side depending upon the rim if comparing against the standard OEM 11/51. So I'm assuming these measurements are within the load tolerances on the wheel bearings so vibration or premature wear does not become an issue.

OK. But the wheel and tire are essentially operating together as one unit. You'd need to elaborate so i understand the technical aspects of the point you are trying to get across. I've always had an interest in the aspect of wheel offsets and the effects they can play on a car where things are moved too far off the standard. Any advice/knowledge is appreciated.

 

I think I understand the point being made here, although Paul's approach is scientific to the mm, while Denis' approach is more empirical, taking into account an element which the tire calculator cannot take into account. The way the tire sits on the wheel.

I have attached my "artistic rendering" of this discussion. Denis advocates that the way the tire spreads over the 12 width wheel it reduces its height in the corners, vs the way the tire bulges on the 11 width wheel, and this makes it look better even if according to the wheel calculator it seems to sit further out.

Look at a ruler to realize the width of the 2mm that we are talking about, its not 0.2 of an inch, but of a centimeter. That is tiny! And could be explained by the way the tire spreads on the wheel, at the absolute corner of the tire...

 

LOL at my drawing. Gawd.

 

Thanks everyone for their input. I will 'mock up" the wheels and see if I like it.

Nick,

I like your idea about "reversing" the idea. Like you said I'm not skilled enough to Photoshop that! But I have friends that are... Maybe I'll just leave the wheels alone and use the money for my custom exhaust..

I REALLY like those D2 wheels.. They are awesome.. Pretty pricey though..

I like the BBS 's that Denis is thinking about as well.. They would look great on his new car.. I have to agree about the black wheels.. I like a polished lip as well.

Where I live every pimped BMW to Scion has black wheels..

Although Nick's car look beautiful with the black wheels. But it's a Turbo with those big red calipers.. It just "works".

Thanks again for all the input. I'm really leaning a lot for this forum..

Phillip

 

19x8.5+51 are 24.3 lbs and 19x11+56 are 26.3 lbs. Both are very high, conservative offsets that reduce the backpad material for better weight.

The Forgestar F14s are available in 19x8.5+45 at 23lbs and 19x11+40 at 26 lbs with the same flow forming technology as BBS for 60% of the price in the US.

A well engineered forged monoblock wheel in those specs will weight 18 - 19 lbs front and 21 to 22 lbs rear.

You quote EURO prices, which have always been notoriously lower in EU than in the US. It's a case of apples to oranges here.

 

Stock Turbo Wheels
8.5x19" 23 lbs. 8 oz
11x19" 27 lbs. 14 oz.

BBS CH-R 12x19 ET 45 - 28 lbs. (12,8Kg)
BBS CH-R 11x19 ET 56 - 26 lbs. (11,9Kg)
BBS CH-R 8.5x19 ET 51 - 23.8 lbs. (10,8Kg)
BBS CH-R 9x19 ET 53 - 24.5 lbs. (11,1Kg)

Again , boat anchors ??

BTW, Forgestar offsets and rear width are wrong for me. No use for them even if they were cheaper than BBS.

 

The Forgestars can be made in 19x12 as well. The usual fitment on 997 widebodies is a 19x11+40 - that offset is spot on in regards to fitment.

 

Maybe for you, for sure not for me. But going back and forth with a wheel seller is not what I like about a Porsche forum so I'll leave it at that.
I only called you out on the 'boat anchor' remark. It's wrong and you know it.
It's a shame vendors have to knock other products down if margins are not good or they can't get them.

 

Paul, when I have more time I'll try to explain it better. Not easy in a foreign language, you know. But Nick's drawing is not that far of the mark.

First I have to get this out of the way :
https://rennlist.com/forums/9572462-post44.html

 

Thanks but no need for drawings. I understood what Denis was saying about the pulled sidewall creating more clearance than a vertical sidewall. Just don't hit any big bumps lol. Imo 305's hardly look baggy on an 11"rim, more vertical than an opposite angle. The wheel protector bead/rim is also there on street tires whereas on R spec such as Michelin PSCups the bead is not there as seen on Denis's GT3RS photo. The protector bead can give a visual appearance the wheel is sitting out further than what it is, however pulling the the sidewall of the tire can make the street tire look more visually angled than what would be the case with an R spec tire. How do i know? Because i have a separate set of rims with R spec tires on them and the look it gives is quite different to the sidewall on my street wheels and tires. So, this needs to be taken into consideration especially if aesthetics are the main goal here....which appears to be the case i.e. lowering and using more aggressive offset wheels etc. And not saying there is any right or wrong using 12's with 305 street tires....but there is relativity where aesthetics are concerned. IMHO of course

And if lowering is the clear/main objective along with having no requirement for spacers then the 19 x 12 ET 45 will certainly do that trick.

Absolutely. When cast and forged and are concerned there are clear advantages....hard to argue that .

Ultimately at one point it all comes down to dollars and what one expects in performance terms.

BBS are obviously good quality rims or Porsche wouldn't use them as an OE supplier.....although i note Porsche has used mainly forged offerings.

Lol...but quite funny in a metaphorical sense.

And to add to the weight chart;

OEM 19 x 8.5 ET56 - 23.98lbs (10.9 Kg)
OEM 19 x 11 ET51 - 28.82lbs (13.1 Kg)

For reference purposes i weighed up my stock rims on our warehouse digital scales. The scales are accurate.

So where the CHR's (8.5 and 12'S) are concerned there is no weight penalty (or advantage) over and above the stock forged oem rims. Maybe a slight penalty on the fronts.

 

What timing that I find this thread they day my silver BBS Ch-R's were delivered. I went with the 8.5 up front and 11.0 in rear. My car is GT Silver like Speed21's and I just don't know whether the color is going to look right. I am going to do a test fit today to get some other opinions to see if the color of the wheel is too close to the color of the car. While I love the color, I find the machined finish (as the stock wheels are done in) to look best against the GT Silver. If I determine that these CH-R's color is satisfactory with the car color I will have the tires installed (305 rears) and post additional pictures.

As far as being boat achors -- that is a ridiculous comment to make. I had Forgestar F14's on my 997S and they are great wheels as well. Not going to knock them.

Another thing to keep in mind is that the 11" rears are 2lbs lighter than the 12" rears.

As far as price goes -- I got mine from Tire Rack for $2,750 delivered..... to my door (in 3 days).

 

Good choice !!
Yeah, that 'boat anchor' comment made me all defensive. What a comment to make from a 'pro'

Anyway, the 11 in the back will need a spacer.(5 mm is fine) Otherwise they'll sit to deep inside the wheel well.

Price you got seems good. I am paying for mine 1600 euro (8.5 and 12) which comes to around $2000. I have to get them myself but the vendor is close enough.
Just ordered them btw, picking them up next Wednesday.

 

Lots of pics Denis. And mask those calipers with red tape so it will look like my car! Ha...