speed21

One thing i noticed looking at Tireracks list of CHR's was they had a variety of rear offsets with some going the other way in (ET 60). Sheesh, you'd really want to be on your game to get the right ones....else you may wind up with a shopping trolley. The OZ's all seemed to stay around the 51 to 55 ET on the fronts as well so they too don't stray too far off the standard. CHR had 51 on front so with the stock offset of 56 that'd give 5 mm extra on the outer....so would help with having no spacers on front.

TT-911

Always nice to read peoples opinion on wheels. Usually it is a lively subject

I have been in the wheel business for the best part of 25 years. 12X19 ET45 with a 305/30ZR19 is perfect. Lowered or not.
But anyway, my Techart springs are ready in my garage.

Why do they fit? Because you can't just look at the wheel alone. The 305 tire on a 12" will stretch, instead of looking like this \ / it'll look like this / \ , so the tire will never rub but from appearance (sitting on the wheel) they will look more like the front wheel/tire combo.
Look at your 11" wheels and 305 tires. They look bloated compared to the fronts. When the 305 is used on a 12" you get that perfect fit just like the front. This pictures tells it all, this is a 12" ET45 with a 305 stock tire. No rubbing, no nothing, just perfect. How many times I haven't come across the guy with the chart claiming this or that to be a problem. You are not just mounting wheels but a package of tires and wheels. The package has to work. It does here :

TT-911

The higher ET's are for narrow body 997's.
For WB BSS makes a 9X19 ET53 (or 8.5X19ET51) front and 12X19ET45 rear.
Thos are perfect with the stock tires.

speed21

Yes i figured that must be the case. I also note the GT3.2 is running 12's with 305 tires so they obviously fit. A couple of the wheel guys i recently contacted said the 305's are a little pulled but are fine on 12's. I guess the optimum tire size for 12's is 325? So do you sell wheels for our cars Denis?

Ps. I also note the GT3 rs runs 8.5J x 19 ET53 with 235's and Rear 12 x 19 ET 51 with 305's....and it can't be said the wheels dont fill the gaurds on that car, even with a lowered ride height, although that said it does have 5mm spacers on the rear so if they came off, the rims would sit back in another 5mm. The GT3RS is a good benchmark to use being a lowered wide body with a perfect wheel position in the guards.

TT-911

No , I sold my company in '05 and retired from the rat race. Enjoying life and family. Still am a (silent) partner in a German wheel manufacturer but they work in a different (normal cars) market.

325 on 12 will create the same look as a 305 on the 11's and that is what I want to get rid off. I dislike the 'bloated tire' look. Doesn't fit a sportscar in my opinion. That is why I am so happy I discovered those BBS 12". Just perfect.

speed21

Oh well....there goes my next question. Shame it isn't with BBS then eh?

speed21

[quote]It's agreed there are differing opinions where the pulled or bloated look is concerned. The Champions seem to have struck the best of both worlds with the 11.5 rear width (IMHO).

So I take you're not pining for a set of forged then?

TT-911

Sorry but what are you talking about ? Boat anchors ? Really ? There is NO alternative to a BBS wheel at 400 euro per wheel. As I said they are light and the casting process is very good. Did you see the weight off those CH-R ? The stock wheels are forged and weight of these BBS's is similar.

Next, you are offering these BBS for 2800-2900 (dollars) and I can get them for 1600 (euro) here local, no freight, no import duties. nothing.
What would you do ??

TT-911

Euh, not quite Paul, you know BBS was under chapter 11 in Germany and is now sold :

http://www.bbs.com/en/company/news/2012_presse_01.html

Very happy I was not a partner in BBS or I might not be driving a turbo today

speed21

Sorry. Not up with what happened with BBS. But good to hear your in a turbo.

Anyway Denis, you being the wheel expert here, and mindful each car manufacturer has their own technical understanding of how their cars will behave/perform with regard to any changes to wheel offsets and the likes, what is your take on how far a wheel can be moved out (through spacers or changes in offsets) before things create handling and vibrational issues?

TT-911

[quote=speed21;9571001]12 combined with 305 is used on the GT3-RS and I prefer it.
Btw, body of GT3-RS is same as turbo and stock ET is 46 (with 5mm spacer). So the CH-R are only a measly 1mm more outside. It's a non issue really.

Forged is nice if there is a (big) weight advantage. These BBS are so good that I see no reason to spent 3 times the money on forged. Also, being an old(er) stubborn wheel guy I prefer to ride with BBS. BBS and Porsche have a loooong history together.

TT-911

That entirely depends on the car. F.ex. the old MB W124 comes with a ET49 if I remember correct. Aftermarket wheels for that car were ET35 or even 30. Car drove very well with them.
Do the same with some VW's and you got a bad driving car.
Usually I would try to stay within 1cm of stock ET.

Spacers is only used as a last option. I preferred not to use them in the past. Longer bolts, more risk of vibration, corroding to the hub. Braking off, I've seen it all. Also you are adding unnecessary weight were it counts. Sometimes you have to but if possible we worked with lower offset wheels.

TT-911

I am sure I am boring by now but here goes again.
You are riding a 11.5 ET44 with a 305, correct ?
If I am on a 12 ET45 with a 305 I will have less risk of rubbing than you.
Attached a GT3-RS with 12X19 ET51 (and 5mm stock spacer, so real ET46) on 305, weight of car on rear right wheel. Still plenty of space and the tire sits so very nice on the wheel. Picture perfect.

Now I'll keep quiet

speed21

Sorry to inform you Denis, but you are wrong with the 11.5 ET44 having the greater chance of rubbing over the 12 ET 45. It's actually the other way around. The 12 ET 45 protrudes more than the 11.5 with ET44.

i.e. The 11.5 44 vs your 12 ET45 using the linked offset calculator shows the 12 ET 45 as protruding 5mm more.

i.e. The stock GTRS 12 ET 51 vs you 12 ET45 again shows the 12 ET 45 protruding 6mm more.

So with GTRS using the 5mm spacer, it reduces the difference down, but the 12 ET 45 still protrudes 1mm more. To be exact.

So as i said before the 12 ET 45 has a very aggressive offset vs the stock tt rim 11 ET51. Not that there is anything diabolically wrong with that.

However, all of this additional protrusion becomes less significant once the car is lowered, and i would agree if lowering is the ultimate intention the 12 ET 45 will sit with the same/similar stance as the GT3RS without the need for using the 5mm wheel spacer, that is if the car is lowered to the identical height specs and set up to the stock GT3RS rear alignment specs.

Sorry to be pedantic, but the above correction was needed to retain the integrity of the very point we were debating.

And to the other point of increasing or reducing offset and/or wheel width beyond a given point off standard, I was hoping your industry knowledge may have allowed you to educate the likely result/consequences of taking things past the manufacturers recommended guidelines. Everything has limits and its knowing those limits that is often the problem when making a decision. Any info is appreciated.

TT-911

Long post but not correct, I stand by what I said
Don't think in terms of wheels only and you'll get it, stretched tires sit lower and narrower on top.
For ex. 11 et40 is worse for a turbo than 12 et45 with similar tires. The load of the wheel is devided inside and out giv 6 mm diff on the outside. On the 11 et40 the load is complete and only towards the outside , so 11 mm. What do you think is better ?