BBI rim sizes

I believe the wheel specifications shown in the 224/81 BBi OM of:

Front 180 TR 415

Rear 210 TR 415

translate as the distance from the inboard bead contacting surface to the outboard bead contacting surface being:

Front = 180 mm = 7.09 inches

Rear = 210 mm = 8.27 inches

(and the bead contacting diameter of both is 415 mm = 16.34 inches)

 

Yes, it is a little unusual to have the same size tire used on two different width rims on the same car, but, aesthetically, it does look better as the wider wheel at the rear makes the rear tire shape wider. Later, Manufacturers decided that making the diameter of the front tire smaller and less wide than the rear looks (and performs) even better (so that's how virtually all performance cars are now). Don't know if you can do this without needing to make ride height changes and/or rear fender flares (and know that it's blasphemy ), but rather than running 240/55-415 tires all around, I'd wonder if using something like 240/45-415 tires at the front and 280/45-415 tires at the rear would "modernize" the look of a Boxer even more -- just a thought...

 

Yeah, that is why folks (me included) have gone to the aftermarket 17inch rim. Better rubber and more sizes to play with. No matter what size TRX tire you put on it's still a crappy TRX tire.

 

A picture. 17 inch Group 4 wheel. Conti extreme contact sport tires. Image Unavailable, Please Login

 

I've got the 17's as well and put P Zero's on them..it seems to work really well.

 

But they have a nice tread for off road use..

 

LOL!

 

I thought about going this route a few years ago. Here are a few more pics of the Group 4 wheels! Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login

 

http://www.group4wheels.com/phone/index.html

I've had them almost two years. They are well worth the change. I have much better tires which gives better handeling. Much better handeling. I have 245/45/17 front 255/45/17 rear. Probably would go to a 225/50/17 front next set.

Bottom line, get a set of these rims.

 

fitting wider rims inside the same size tyre will slightly change the character of the tyres Performance. It is very Ferrari to have a suitable size rim on the front and stretch the tyre onto t he rear.

Sadly the 280/45R415 TRX is no longer made.

 

Oo, not really true. The TRX was pretty epic technology, and they are great tyres. It depends what you are judging on. the 415 TRX will give a much nicer ride than you 17" wheels, as the TRX technology is very clever at absorbing the shovcks of the road.

Hopefully this page explains about the TRX https://www.longstonetyres.co.uk/michelin-classic-tyres/trx.html

 

I have a MB for comfort. I bought both my Ferraris for the driving experience and long ago switched over to 16 inch rims on my 83, 308qv. Sorry, I get you provide vintage tires like Avons, Michelins and others which are great for 13, 14,15 inch rims. I had XWXs on my '69 TVR Vixen back in the day. Had XVS on a 65 Jag.

For me theTRX tire/rim was not a success and was quickly scrapped by those manufacturers who bought into the marketing. Are all rims and tires manufactured that way now? Nope. Thus, leaving all those who had a car with these rims at the mercy of waiting for a production run and paying a princely sum for a forsaken tire/rim idea.

 

I’d say that was a little cynical. the TRX are great tyres. A lot of the technology that was in TRX got used in modern tyre construction without getting the full benefit of its unorthodox flange. So if you are fitting a rim of a very similar diameter and a slightly later tyre carcass design from a top manufacture the the difference will be minimal. However when the wheels are a couple of inches taller It won’t absorb the vibration as well which has more consequences than just comfort. It protects the other components in the car.

if you are thinking that fitting a more generic rim size means that you can fit a budget tyre because it is better than old crappy technology you are barking up the wrong tree. Fitting appropriate technology gives a better drive and Michelin make better tyres than the majority of other producers.

I’m not saying fit 17” wheels will shake your car apart. And fit budget brand tyres and you will crash.

however what I am saying is that TRX tyres are good appropriate technology. And bigger wheels compromise the tyres abilities to absorb the shocks of the road from a comfort point of view and from the angle of protecting you car.

also is it false economy to fit big wheel to fit cheap tyres?

 

Jonathan Sage, Group 4 Wheels Ltd
+44 1225 430 502 or +44 7971 988 735 [email protected]

they had them discounted In early 2018 trying to clear inventory. You might buy three of each since highly unlikely to be made in another run.