Question regarding correct Spider Alloy sizes for Cerbera

[mikeinsheffield]

Hi Guys,

Please could I just ask for confirmation on the correct sizes for the 18" Spider Alloy wheels for the Cerbera?

I've just collected my "new" set from being refurbished, and just wanted to confirm that I have the correct size alloys before thinking of maybe buying some stickier rubber for occasional track use on a second set of alloys (I am running Eagle Assymetric II's for road tyres on 18" spiders for everyday use).

These are the numbers on the inside of the wheels:
R 8.5J x 18 H2 +33

Front 8.5J x 18 H2 42
F 5J x 18 42

Are these the right size for the Cerbera? I assume 8.5 means the width of the rim in inches, what do the +33 and 42 mean? Is it something to do with offset / spacing ?

Thanks for your help (in advance)

[Steve_T]

Yes 33 and 42 are offsets. This is the distance between the middle of the wheel width ways and the face of the wheel. Some Cerbs took Tuscan fronts all round (42mm offset), some the later cars are fine with Tuscan rears on the rear (33mm offset).

Better (pictorial) explanation here: http://www.rimstyle.com/pages/alloy_wheels_explain...

[Gazzab]

Very few cerbs left the factory with rears on the rear. Most came with fronts all round. My late cerb has fronts all round. You might be lucky and get no rubbing with rears on the rear. Think it will only show itself whilst under hard cornering or when you hit a depression in the road.

[Jabbah]

I've got 33 offset on the rear and get bad rubbing. Never got round to replacing them but it's on the list for this year.

[Jabbah]

Couple of pics:

Edited by Jabbah on Wednesday 25th February 13:06

[TA14]

Jabbah said:

I've got 33 offset on the rear and get bad rubbing. Never got round to replacing them but it's on the list for this year.

IIRC the standard size is 8x16 et35. I suppose that by going wider to 8.5" you need to increase the offset, or amount pressed in (einpressetiefe ish in german to give ET) to avoid rubbing on the wheel arch. The factory 18" (non spiders) had a different offset but I can't remember what it was.

[Jabbah]

Gazzab said:

Think it will only show itself whilst under hard cornering or when you hit a depression in the road.

Pretty much every undulation on the motorway. Was really bad on the way to Le Mans with a full boot and large passenger.

[mikeinsheffield]

Thanks for the quick replies guys!!

Sooooo.... if I understand this correctly (thanks Steve T for link to techie explanation) the larger the number, the further "in" towards the centre of the car the wheel sits? Therefore the Rear sized wheels at 33mm sit 9mm further "out" from the hub than the Fronts (at 42mm), is this correct?

And this 9mm difference is enough to cause the rubbing on the rear wheelarch?

I must check the current spiders I have on mine by taking the wheel off and seeing what type of wheel / offset I am currently running....

Mine is a 2002 later shape Cerb - I don't supose that this makes any difference?

And BTW - if a "rear" wheel doesn't fit the rear of the Cerb, what is it the rear wheel off? The T cars ???? (Tuscan, T350, Tamora ???)....???????

[TA14]

mikeinsheffield said:

Sooooo.... if I understand this correctly (thanks Steve T for link to techie explanation) the larger the number, the further "in" towards the centre of the car the wheel sits? Therefore the Rear sized wheels at 33mm sit 9mm further "out" from the hub than the Fronts (at 42mm), is this correct?

Ignoring the words front and rear in your quote, yes, an ET33 will sit 9mm further out from the hub than an ET42.

mikeinsheffield said:

And this 9mm difference is enough to cause the rubbing on the rear wheel arch?

Maybe. Whether it rubs is down to a number of factors: exact choice of tyre (manufacturer and model,) the spring stiffness, condition and length, also the dampers, the body shape (the exact shape and thickness varies slightly from car to car) and the suspension settings to name a few.

[Brummmie]

I run 10" rears with a 50 offset, they dont rub, there is lots of space before you clout the suspension, i could go even further than that i reckon.

[pmessling]

i had rubbing with rears on the rear, swapped over to fronts all round. it was worse with a load in the boot but general driving wasn't bad but not something i wanted to live with.

[greenracing]

Another tvr trait ... Mine t nd fronts on the front and rears on the rear without rubbing. What tyres sizes are people using that have rears or fronts (on the rear) that rub?

[Jabbah]

greenracing said:

Another tvr trait ... Mine t nd fronts on the front and rears on the rear without rubbing. What tyres sizes are people using that have rears or fronts (on the rear) that rub?

I had it with the crappy Chinese ditch finders that came with the car and also the Federal 595 RS-R
255/35 ZR18 90W that are on now.

[RichV6]

Federals seem considerably wider than toyos across the treads for the same size tyre. Toyos are fine whilst the federals rub. That's 17" rims though.

[Incognegro]

I ran 18" Tuscan spiders on my Cerb with no issue. Had the federal tyres and no probs. however I now have Toyos on my 18" SP12s (same offsets etc) and that setup makes me so much happier