What is the front and rear width (inches) of the BBI rims?
BB 512i OEM wheels are 415mm x 180mm front and 415mm x 210mm rear. This equates to 16.33" x 7.08" front and 16.33" x 8.27" rear.
As far as Boxers, Ferrari went metric (wheels/tires) with the advent of the injected variant (i.e. later-1981). As you already well-know, the wheel dimensions are stenciled in black on the outside of each wheel. Interestingly, although the rear wheels are a bit over 1" wider, the OEM tire size is the very same on all four corners (240/55 VR415). The succeeding Testarossas also had a 415mm wheel/tire diameter (i.e. in the earlier part of the production run), but with wider rear tires than fronts. The 400i cars received metric-sized wheels and tires starting in 1979.
Unfortunately I do not have those stickers anymore. Back in the day, I had those wheels HIGH POLISHED and painted. Since then I brought it back to stock, but never replaced the wheel stickers. Image Unavailable, Please Login
Two friends have those and theyre really really nice. Plus modern rubber is transformative for a BB. Just dont go too wide in the front.
Those metric tires were designed for a 6 series BMW, they had no buisness being put on a ferrari, they were crap even back in the day, all bendy sidewalls and snappy. Story I heard is Enzo had soem deal with Michelin. Meanwhile Lambo and porche went tot he P7 for good reason while ferrari stagnated on tires. Its an easy fix these days and transforms the cars to such an extent in ride, grip and on the limit predictability that the michelins should be considered a hazzard. Tires and waking up a BBI motor are the difference between a car that never quite made its mark back in the day, to somethign that now can be considered a superlaitve machine from any era. or as I like to say 288 experience for 1/10th the price.
Pirelli are making the P7 again. https://www.longstonetyres.co.uk/pirelli-collezione/cinturato-p7.html And if you are looking for tyres for Porsche & Lambo and if you are going 16” on a 308 they are probably the best tyres. Because they are the only set up of tyres that are built to suit that kind of chassis. however it is misguided to think the TRX were crap. In period the TRX system won in F1 and Rally’s. They were and still are feet tyres unless you are driving on old rubber.
The TRX system was uniquely metric and related to the way the tire bead contacted the rim. The TRX road tire available was suitable for a 6 series BMW luxury Gt, not the crop of mid engined cars that appeared in the 70s. Im sure the TRX system could also have developed a lover profile more apropriate vesion for say a BBI but that did not happen probably due to limited volume. My point is not that the p7 should be mounted now, but that back in the day they were infinitely superior to the TRX offerings which were not developed with a focus on a mid engined high powered car. The flaw of the TRX as developed on a sports car is its bendy sidewall. When you start to corner hard the sidewall flexes to an obsene degree, then when grip is lost at the limit(which is lower than a p7 in any event) the tread not only looses grip but thats hugely magnified by the elastic sidewall snapping the tread back under the wheel. That makes recovery way way more difficult because not only is the car sliding but the sidewall elasticity is slidign the tread even faster, couple that with a tail heavy car with the crank mounted high and you have disaster written all over the place. P7s were snappy back in the day too, but not to the TRX degree and you could go wide rear on a P7. I guess to be kind we could say the TRX imporoved grip over what was before, but the sidewall was not up tot he tread grip and worked against it heavily. The answer was the advent of the low profile tire, namely the p7. Ferrari didnt fit a TRX to the 288 for good reason even though they still saddled the BBI and the first Trs with them. Enzo politics related to racing. Its not as though the TRX offered any advantages in any way, it was all downside. Theres areason why ferrari wanted 42 psi on the TRX tires, one of which was to try limit sidewall flex. Even without the heavy rear, that flex does the steering no favors. Had there not been politics relating to using the TRX or Enzo not just been old and stubbporn the BB like the countach and porche 911s should have gone to a low profile tyre. Today we can have the best of all worlds,, a lowish profile 17 in rim that looks oem sporting modern tires with not only great grip but predictable breakaway and still way better ride than a 42psi TRX. Drive a BBI with 275 rears(which fit easily) and the ear is so planted the idea of it breaking away catastrophicaly is really a non thought. In fact small rear slip can easily be detected early and corrected. Its the way the car should have come and would have come but for Enzo and politcs. 275 rears with 225 fronts, you have a really plated rear and a responsive light helm, the car has balance. Maybe a low powered better balanced and lighter 308 can get away with the TRX, on a BB theyre inapropriate and the achilies heel of the car for any serious driving. Or one can go with BB 15 inch rims and new avons.
on my Renault 5 Turbo 2 there have been originaly also TRX. in rain absolutely not driveable and when dry street to hard. I never had real good feeling when speeding, too nervous the car. I changed then to gotti 15 " rims and yokohama and it was like a complete other car
Gotti do make some cool wheels. I think Renault over tyred that car. also 340mm wheels on the front and 365 on the back is a little crazy, but a 220mm section tyre on the back has to be too much for that little car, 190 on the front can't make the steering nice. must be pretty slow and lacking precision. I have a Renault 5 Cleveland Cabriolet which I bought recently I have fitted that with145R13 Pirelli Cinturato, but haven't test drove on them yet, as the water pump bearing is squealing so I am fettling that before its next outing.