Non-metric wheels for 512BBis

they look perfect in the rendering! i could get interested in these wheels in short order. price will be important however.

pcb

 

http://www.ferrarichat.com/forum/135791587-post1.html

A very quick scan of tirerack.com shows no overlap of manufacturer/tire in the sizes suggested. This always seemed to be the curse....

<QUOTE>
Ideal tyre replacements : Front – 225/55/17 (TRX diameter 679 mm)
Rear – 255/50/17 (TRX diameter 679 mm)
</QUOTE>

 

I went with 245/45-18 275/40-18 on HRE 505 wheels.

Stock BB Tires OD
215/70-15F 26.85
225/70-15R 27.40

Stock BBi Tires OD

240/55/16.33 180F 26.73
240/55/16.33 210R 26.73

I went with these sizes as I needed 18 inch wheels to clear the larger brakes.

245/45-18F 26.68
275/40-18R 26.7

 

Yep, clearly a lot more options with the 18" rim. Your fitment is fine on the OD dimension. I think 275 (10.8") is the absolute max you get away with on a Boxer. It's the section height that takes the hit. Only 4.33", which is a 16% reduction from the BBi and a 30% reduction from the BB. It changes the look of the car somewhat.

 

18 inch rims dont work, the whole wheel assembly goes up in weight and you loose the sidewall depth which is part of the look.

I have 17's on my car now 245 45 17 fronts and 275 40 17 rears. They work great and fit great. the car is marginaly lower. If the wheel ofsets are done right the rears dont stick out from the bdywork in the rear more than stock and the fronts in any event are more or less the same width

Modern rubber has different charateristics so it depends what type of tyres you use, I am running ps2's. The steering is significantly lighter and more informative than the TRx's, but I also run less castor and more negative camber than stock. There is a whole world of tactility through the wheel to be gained from modern rubber.

Dont forget that the stock alignment setup is very much for TRx's. In my experience the TRX is a really crappy tyre. Apart from poor grip by modern standards, the really big issue is lateral sidewall flex which is massive on the TRX. This means that when cornering hard on TRx's the wheels are a good few inches further out from the tread than going straight.

When the limits are reached on a TRX and the tyre lets go its with a snap because not only has adheasion been breached but now the tread is also moving at an even faster pace sideways to get back under the wheel due to the elastic forces of the sidiewall. It is this charateristic that makes a boxer "tricky" on the limit. Plus as noted this elastic sidewall robs the steering of much feel and blunts response especialy on turn in.

Boxers are setup stock with heavy steering forces and understeer to ameliorate the TRX, although due to the tyre chatcteristic and weight balance a boxer can still let go from the rear abrubtly too, due to weight shift in the rear and unloading the rear by taping off on a bend.

Modern rubber really does solve all this. the steering can be setup for far more lightness and tactility. Precision through the wheel is a benefit of having a lateraly stiff sidewall and better alignment. The tread reacts to the turn of the whel far more directly because there is not a floppy rubberband sidewall messing things up.

The rear is also far more planted both because it has more width, but more importantly because the sidewall once again does not flex lateraly as a TRX does. When adeasion is breached with modern rubber you are definatly going much faster, but its also pretty catchable because the tread is sliding sideways at the same rate as the car, not much faster as on the trx due to the elastic sidewall snapping back..

No question though, if you change the rubber, change the alignment. Dont forget that Nick Masons BBLM was 2 secs a lap faster than his F40. There is great handling potential to be unlocked in any BB. Amazing they came with TRX's which is really a tyre suited to a late 70's BMW 7 series, not a supercar.

 

ferrari put those TRX only on because at that time they had a contract with michelin for the formula 1 cars. but that has been the most bad tires ever on a BB. when it is raining you can forget those tires completly, too dangerous to drive. only positive have been when you go slowly ( even then you are faster than most others ) the TRX are more comfortable. but who wants this on such a car??

I still have a renault 5 turbo 2 ( 2 seater, middle engine, 1,4 ltr and 160 hp ). this car also had original TRX tires. terrible to drive, nearly no grip when the turbo power explodes. so I put yokohama on - perfect

also the TRX tires are sooo expensive. so no need to have such rubbers.

I have on my BB front 225/50-15 on cromodora 7,5 x 15 and rear 345/35-15 on cromodora 11 x 15, and this works pretty fine


also I have here for a BB used GOTTI rims, 3 pieces. size just now I don´t know. if anybody interested please send a pm.

 

I would be interested but probably could not afford the cost . There has been several attempts over the years to reproduce a Boxer wheel and at the end too high cost especially when you have to shipped them to the states where only a few of us will be interested.

Buy i do wish you luck and this goes thru.

 

This is the first wheel option to come along that truly looks original in appearance, it looks fantastic. I have heard of this company before, due to my ownership of a De Tomaso, they make a great Mangusta 10x15 inch rep wheel, for less than £450. If the Boxer clone is anywhere in the same ballpark, it is a bargain. If I still owned a Boxer, I would be jumping right now.
Group 4 Wheels - Reviving historic rally, road and track motorsport wheels

 

Nice assessment; thanks! I see you moved on from the 16" BFGoodrich setup...

 

I did.

 

What is the weight of these rims,offset numbers and width?

Weight is important and so is width.

To maintain proper scrub radius with stock king pin inclination one needs to make sure if the width comes in sizes to allow size variation in tires through the years,that it will be such as to not alter the front end geometry too much mostly with the fact that if one went with lower diameter front rubber than stock the center of the tire contact has to stay close to stock ,even more so if alignment is altered to enhance the potential of modern rubber with additional static front negative camber.

If the front end gets set up right on these cars the rear is fairly easy as it can have amazing amounts of grip if the shock rebound setting are set on all four corners properly for the spring rates you might choose.

Personally on the street I found I loosened the grip slightly at the rear to let the front control the car more for more fun ride.
You can set these cars with sticky tires to hold at the rear like crazy even with an ignorant driver that might go in a turn too fast and resort to brakes at the wrong time.
The factory has them designed for the rear to not loose grip and the front to have tons of understeer ....enough to scrape of speed with enough steering lock instead on braking coming into a corner and then balance your way with acceleration out of the turn with the throttle and steering lock.

My Etoiles on the Boxer 8.5x17 front and 10x17 rear weight around 24-25 pounds each with the BBi splines bolted on.

Mario

 

The original TRXs were nice tires in their day if proper tire pressures were used up to 150 mph
One of their largest advantages with high profile sidewall and large diameter tire was comfort ,directional stability in all weather condition including snow!

The ones made for the early TRs will fit BBi rims and they were the same width at front (245) and 280s at rear with a ten percent reduction on sidewall profile and the same exact tread pattern as with the 245-55 that were on all four corners on the BBi.

Interesting design trick that proves the severe understeering set up desired by the factory to keep the inexperienced safer was to install 245s with 55 high profile at front on a rim that is 180mm wide.
At the rear though they get a lot more grip by using a 210mm width with the same tire which had 245mm sidewall width but a tread about the width of the rear rims.

To run tires with high profile as 55 percent as suggested here defeats the purpose of getting away from the TRXs

What is the ET or of set of the rear wide cromodoras?

It sounds like you run 24.5 diameter tires at the rear and less at front if these figures of the tire size are posted right?

Mario

 

So can someone verify that the actual spline drives used on early TR wheels are the exact same as used on BB wheels?

 

Hey Steve, great site! Do you know if they actually make those wheels or are those commissioned individually? I saw no price or availability. 8s and 10s on a Boxer look unreal. Hope you're doing well.

 

Price seems fair. I would be a prospect. I hate my TRX wheel/tires. But, they look nice!

 

1800 a piece?

 

Hopefully that is the price for a set

 

Not unreasonable

 

Agreed. I believe that's about 2700 USD before shipping.

 

I would probably buy 2 sets if the first one works out OK.

 

Can you provide us more information on the paint finish?

What is the paint code and will they be painted plus a clear coat?

 

For the price quoted I will take a set

 

If the offsets and quality are right, I'll be in for a set plus a spare. Anyone in Group 4's area to see how these turn out?

 

If the color matches original I would be in for a set.