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Yes the shallower concavity is the front wheel. BBS is very conservative and prioritizes performance. When we first worked to get these made we wanted as much concavity as possible. The engineers at BBS wanted to preserve strength, minimize weight, and maintain caliper clearance. As I didn't do the FEA myself, I trust that the company with one of the best racing wheel pedigrees in the business knows what they're doing...
9" et50 fronts vs stock 8.5" et61 fronts will push the wheel edge further out +17 mm. That sounds like a lot. Would the equivalent of a 17 mm space on stock wheels not rub or extend beyond the fender edge?
i think the rubbing with ET50 has to do with alignment.
last friday, i had
265 hoosier on 9" ET50 front
245 RE71R on 9" ET50 front
and YES 265 RE71R on 9" ET50 front
there's no rub on fender, it will rub the brake duct at full lock. i cut half of the duct off.
i dont recall the ride ht of the cars. but both test cars had at least -3* of camber up front. and the one with 265 RE71 sits very low to the pavement.
9" et50 fronts vs stock 8.5" et61 fronts will push the wheel edge further out +17 mm. That sounds like a lot. Would the equivalent of a 17 mm space on stock wheels not rub or extend beyond the fender edge?
marty, not sure if you had a change to look at my car both the blue and the gold bbs are ET50 with 9" width. it does'nt stick out too far, but it's very flush
i think the rubbing with ET50 has to do with alignment.
last friday, i had
265 hoosier on 9" ET50 front
245 RE71R on 9" ET50 front
and YES 265 RE71R on 9" ET50 front
there's no rub on fender, it will rub the brake duct at full lock. i cut half of the duct off.
i dont recall the ride ht of the cars. but both test cars had at least -3* of camber up front. and the one with 265 RE71 sits very low to the pavement.
ShakeNBake experienced some rubbing with 265 hohos; but he didn't care about it.
Now stating just the camber is only part of the story when caster is not mentioned. All play together. At the same token we also have the caliper/wheel clearance to deal with because of debris that could get inbetween and mar the finish.
I also think that the math for an offset needs to take in account the section width of the tire being used: i.e. 245 on 8.5 vs 245 on 9 wheel where the wheel have the same offset.
my caster is adjusted. the wheel is dead center on the wheel well, no rubbing mark on the wheel well liner that i can see. no rubbing mark on fender lip either.
i ran E88 BBS, if you do static alignemnt and put wheel wts on the inner barre closest to the edge (center of car) it will clear caliber. if u put wts near the back side of mesh then it will hit the caliper if rubber or debris is caught.
and i agree that 245 on 8.5 should be compared with 245 on 9 bu ti only have 9" front.
orthojoe has 8.5 eT50 with 245 RE71r. he has no issues rubbing. i dont know his caster, but his camber is b/n -2.5 and -3.
unfortunately these tolerances are so close that it's really alignment dependent has you mentioned.
and tolerance of wheel/rubbing etc also depends you drivers tolerance.... i got 19" to fit over pccb with 1mm clearance. the wheel will rotate freely no issues but if the barrel has ANY deflection at all... so in that case, i dont think it fits over pccb.
but for ET50 19" front , i personally dont have rubbing issues other than the cutting of brake cooling ducts.
Talked to BBS as well and they've been selling E88's in 9" ET50 for some time now. We're getting a set (having them painted BBS gold) for our GT4 with 265 R7, 295R7 and will document alignment ride height etc. I believe most have this covered
Order for Motorsports silver and Satin Titanium going in tomorrow...
06-18-2016, 11:51 PM
BBS 19" Monoblock Fitment for GT4
