General Sei Alloy Wheel confusion

[f1ian]

Hi All.
I am looking to upgrade the wheels and tyres on my Sei Sporting. I am currently on 13" and want to stay like that. Unfashionable maybe but it's what i want and Yokohama make some great track tyres in 175/50 x 13

Anyway, its the wheels choice that i am stuck with, I understand that Sei/Cinq have around 30-38 for the offset but i have 27.5 cast into the wheel.
Since the rear wheels are close to the arm at the back anyway, i thought i should "Measure Twice, Spend Once" so i popped off a front wheel to check. I have a 5mm spacer on the hub - is that normal since i don't have Abarth wheels? - and i measured from the back of the wheel where it contacts the hub to the back edge of the rim. I measured 115mm.

So where does 27.5 come into it??? Or 30-38mm offset for that matter?

I plan to stick at 5.5 or 6 x 13 so nothing too radical but there is a lot better choice of wheel at 4 x 100 PCD so i was thinking to use PCD adapters as i don't like wobble bolts. The adapters are all around 20mm thick so that could complicate things. I dont want to end up with wheels outside the arches or upsetting the steering feel. The alternative is to get a set of custom wheels made but at what offset?

Thanks in advance for any advice.

 

[f1ian]

While having a good think, I may have answered my own question. For anyone interested, this is what I think although please correct me if you know more!

The wheel spacers- I was reading the threads aboutUno turbo brakes, it is mentioned in a few places that's pacers need to be machined down to fit behind the Uno disc so I am assuming my spacer thing is normal.

Offset.- a 5.5 inch wide wheel is around 140mm. The centre line of that wheel therefore is around 70mm. Add an offset of 30mm and you get to 100mm. My measurement was 115mm. so where did the extra 15mm come from?
I have not been able to actually measure a Sporting alloy without tyre but I bet is would not be 140mm wide. I am not sure in this case but think it is common to give a width measurement for a wheel to the point where the tyre bead sits rather than the actual edge so you could expect a few more mm outside of this point. I think this is where my extra 15mm comes from.
If I am right then the maths roughly add up and the information that Seicentos have a 30mm offset is correct.

All I need to do now is find some nice wheels in 13" that come close to these measurements and I will be happy!

 

[David C]

Wheel width is always the tyre seat area. So the overall width of the wheel is always more. Could easily be 1" more for an alloy. So yes, that is where your extra 15mm is.

The offset of your wheels will be marked on them somewhere.

 

[rallycinq]

I might just happen to have some Compomotives....

D

 

[f1ian]

Wheel width is always the tyre seat area. So the overall width of the wheel is always more. Could easily be 1" more for an alloy. So yes, that is where your extra 15mm is.

The offset of your wheels will be marked on them somewhere.

How about that, I have proved that I am not as stupid as I thought I was! I blundered into the correct answer, thanks for the info!

 

[f1ian]

I might just happen to have some Compomotives....

D

Compomotives you say??? a photo and model/spec may tickle my fancy....


(although my daily driver just kicked me in the pocket to £1600 so I am having to make tough choices at the moment - food or beer but not both, that sort of thing)

 

[David C]

How about that, I have proved that I am not as stupid as I thought I was! I blundered into the correct answer, thanks for the info!

On a similar theme, we've had people that are convinced someone has put 13" tyres on their 14" rims ..... (they've measured the wheel with a tape measure)

 

[rallycinq]

Compomotives you say??? a photo and model/spec may tickle my fancy....


(although my daily driver just kicked me in the pocket to £1600 so I am having to make tough choices at the moment - food or beer but not both, that sort of thing)

They are a long way away, next time I am up at the shed, I'll have a look.

Cheers

D

 

[Eklipze3k]

On a similar theme, we've had people that are convinced someone has put 13" tyres on their 14" rims ..... (they've measured the wheel with a tape measure)

https://www.fiatforum.com/cinquecento-seicento/188929-o-crap-lol-please-help.html

I love that thread!

 

[f1ian]

https://www.fiatforum.com/cinquecento-seicento/188929-o-crap-lol-please-help.html

I love that thread!

I ate a whole packet of Jaffa cakes while reading that thread. Everything I ever needed to know about tyres but was afraid to ask... I think I can consider my confusion fairly minor compared to some others!!


I am still wondering the best way forward with wheels, the choice at 4 x 100 PCD is so much better. I have never liked the sound of wobble bolts - it does not sound like much of an engineering solution. I also don't really fancy adapters - having run them before and had nothing but wheel vibrations.
If I end up with 4 x 100 wheels I can see myself getting the holes re-centred then use sleeve bolts since I have a terrible habit of overcomplicating any problem that I come across.


Converting the car to 4 x 100 is another option and gives limitless options for eBay crazy purchases. I once had a PCD changed by re-drilling hub flanges and press fitted studs into the new holes to mount the wheels. Not to painful at the back but was more involved at the front due to drive shafts running through the hub.


Anyway, many thanks to those who posted advice and if Rallycinq makes it to the shed I would be interested to see a photo of the wheels.

 

[purf]

Look out for old Alfa alloys but watch out they can be heavy... and usually need 10mm spacers so about £60 & 5kg for steel items...