Wheels!! Help

[olly]

Hi,
can anyone tell me what the maximum rim width i can get away with for my marina based roadster.. ive been looking for rim width 5.5j, but could i get away with a 6j?? help please!!

looking for a set of 15", but alot of them say 6j.. would they fit?? tyres and pcd is correct.

any info would be good! dont want spend over 250 if i can help it..

cheers

olly

[greyV8pete]

Re: Wheels!! Help

Hi Olly.
Can't answer the main question but a dimension that you MUST compare is the offset. This is the dimension from the hub face to halfway betwen the rim edges (when viewed from the say front of the car). It can be checked by putting a straight edge across the hub face and another straight edge across both the inner and outer rims in turn. A 6" ruler and some quick arithmetic will then give a dimension for a quick comparison check. Very simply the offset is designed to get the centre line of the tyre contact patch and the centre line of the steering swivels "king pin inclination in old money" to coincide. If you have the wrong offset you will get some crazy (and dangerous) steering effects as well as dramatically increasing loads on the steering, ball joints etc. Bin there. Done that. Sold the wheels soon after. Got the Tshirt! Peter.

P.S If you change rim diameters from original you must change the tyre ratio size to get the same rolling diameter as this also affects above geometry, as well as your speedo calibration. Local tyre stockists have charts to give rolling radius comparisons or look on tyre manufacturers websites. PL.

[olly]

Re: Wheels!! Help

Hi Peter,

Thanks for you post, as you are probably aware im really lost on this whole finding the right wheels!!

the only problem i have is the wheels that are on it at the moment are old steel ones, and the face of the wheel is near enough in the middle of the rim!!

what does it mean with regards to measuring my offset?? and id like new style alloys on it but im lost to what ones will fit.. i have the pcd which is 100mm, and the tyre size is 185..but apart from that what else do i need??

cheers mate..

any help would be good !!!

[jon_cox]

Re: Wheels!! Help

Hi Olly,
What is your roadster based on. Marina, Triumph or Sierra?? This will determine which wheels you will need.

[olly]

Re: Wheels!! Help

Hi Jon,

marina based...hope you can help me!!


olly

[ROBERT.JACKSON]

Re: Wheels!! Help

I got 15" 5 1/2 wide Alloys from MWS (MIDLAND WHEELS SUPLIES)they have web site. The Marina PCD is 3.75 inch. When speed checked with satnav itis spot on.

[olly]

Re: Wheels!! Help

Thanks bob i had a look but sadly a little out of my price range. is the pcd measured on the diagonal? as the pcd on my current wheels is 4 inches...

olly

[macdonald.dm]

Re: Wheels!! Help

Hi Olly.

Your proposed rim width of 6" is perfectly fine for 185 wide tyres, and will take wider if you wish.

If the PCD is 100mm (4&quot, then - obviously - your new wheels must be the exact same. There is often the matter of the 'axle' hole size in the middle - ideally this should be the same too so's it sits snugly on the hub (it certainly can't be smaller, or else it won't go on. I've heard it doesn't matter too much if it's a little larger as the wheel nuts will ultimately locate the wheel centrally on the hub - but, really, I think it should be the correct size.)

And then there's the offset - basically how far the wheel sticks in or out in relation to the hub. A 'negative' offset means the centre line of the wheel sits further out than the centre line of the hub - the wheel sticks out further the greater the negative offset (if I remember correctly!)

I'm not quite sure just how critical the offset figure is - you need to confirm. As I understand it, the Cortina-based Berli (like mine) came with Compomotives as standard which have a sizeable negative offset - much more than the original Cortina steels - but this has no adverse effect on the steering or handling. But don't take my info on this as gospel!

[macdonald.dm]

Re: Wheels!! Help

Oh, if you remove one of your current wheels and give it a darn good look over (without removing the tyre!) you should find the wheel size on it - diameter, width and hopefully an 'ET' number which is your offset. Look for a negative sign in front of the number. I'm guessing it will be negative as most rear-wheel drive cars were to my knowledge. Front wheel drive cars seem to have +ve. I doubt that's a 'rule' tho'!

[greyV8pete]

Re: Wheels!! Help

Hi Olly. Confucius he say picture better than 1000 words! have a look at the following link from Google Images.

http://images.google.co.uk/images?hl=en&q=Wheel+offset&gbv=2&aq=f &oq=

Lots of diagrams there showing wheel offset, which should answer your question.

PCD is short for Pitch Circle Diameter which is the diameter of the theoretical circle that could be drawn through the centre line of all the studs, so the diagonal is the measurement that you need. (My Hunter is Sierra based and PCD is 4.25inches).

A further important check. If you go from steel to alloy wheels make sure that you get a set of wheel nuts to match the angle of the seats. Steel wheels tend to be about 60 deg conical whereas alloys tend to be about 90 degrees. If you use the steel wheel nuts on alloys it will a) wreck the seating and not torque up without damage to the wheel and b)because the nuts are not seating fully they and the wheel could easily work loose with disastrous consequences! Peter.

[jon_cox]

Re: Wheels!! Help

Hi Olly,
The PCD is measured diagonally. If yours really is 100mm / 4 inch then you have a car that has been modified. To my knowledge (please someone correct me if this is wrong) the Marina came with a 95.25mm / 3.73 inch PCD with some very early models and the 10cwt van having a 114.3mm / 4.5 inch PCD. Morris Minors have a 100mm / 4 inch PCD as do many modern cars. Can you post a picture of your wheels and hubs so that we can help you further....

[macdonald.dm]

Re: Wheels!! Help

Agree with Jon - I'm pretty sure I read on t'web somewhere that the Marina PCD was ~95mm-ish.

I emailed a guy selling original steel 'Ital/Marina' wheels for any info stamped on them, and he sent me this: 4.50 x 13 x 22.3. Ok, I suppose the 4.5 is the width in inches, 13 is the dia, so 22.3 will be the offset in mm? (Guessing there!) He's sure there's no -ve sign in front. So, +ve offset (sticky-inwards) or else the negative sign simply not shown? I just don't know.

Basically, be 100% sure before buying anything! Perhaps contact the Marina Owner's Club for this kind of info - I'm sure they'd also be fascinated with what can be done with one of their cars!! They should surely also be able to suggest where to get after-market alloys - although a quick glance at their site seems to suggest they are obsessed with originality!!!

[olly]

Re: Wheels!! Help

Thanks everybody for your help.. and all of your comments.

ive had a look on the wheels but they have been hand painted so many times the paint must be and inch thick!! so theres definatly no markings or writing on them! sadly..

and jon i will post a picture on here later tonight so it may make it easier for you to see what im dealing with..
but i checked again and its definatly 100mm pcd.

Donnie im hoping your right in the fact i could go to 6inch with 185's as it will make it alot easier to find a set.

the only problem i now have is how important the offset is, as the current wheels have the face basically in the middle of the wheel, so im guessing il have to change my offset what ever happens..

any other comments would be good and il post a pic shortly.

thanks again everyone and maybe with a little more help i can get this sorted and i will post many pictures of the new wheels if i ever actually get them!!

olly

[olly]

Re: Wheels!! Help

hope this pic helps at all... let me know if you need any others or information

cheers

olly

[olly]

Re: Wheels!! Help

ok i dont think the pic is working!!