Tyre Choice

[pep105]

Adrain

For road (and track use) 195/60 14 is a great compromise, as far as i know the original tyre was 165SR14 with a rolling diameter of approx 619.6mm, 195/60 has a rolling diameter of 589.6mm and the smaller tyre size you go the smaller the rolling diameter and the lower the gearing.
Remember the GT1600Jnr has a 4.56:1 single spinner (non LSD) Diff therefore is easy to light up the rear as it is. I have this size on my Jnr and its seems to work fine and its a popular size on lots of 105s due to the balance between grip, steering weight and rolling diameter. 185/70 was a popular size (rolling diameter 614.6mm) as its close to original but tyre choices are limited.
With rim choices 14 x 6 or 14 x 7 is the go with that tyre size and something like a GTA replica wheel which Alfaholics or classic sells in a 14 x 7 with a 24mm offset gives the car a nice tough guard filled GTA stance, clears the steering arms and does not foul the guards. If your going R spec tyres Yokie A0048s, Toyo R888 etc
thing to note is the actual tread width is wider than the size i.e 195/60 may have a tread width of 210mm
so offset is important. In the case of the minilites which are a reasonably priced they come in a range of offsets and poular sizes are again 14 x 6 and 14 x7 with you guessed it 195/60 14 tyres. Check out the alfaholics/classic alfa websites for images it gives a great insight into how your car could look and what other 105 owners are doing
Cheers
Pep

[Scott Farquharson]

Calculator modified to run to 7500 rpm.
Also adjusted 4th & 5th gear graph scales to go beyond 240kph
Exposed gear ratio setting area
Adjusted calculation formula, replaced the value of Pi which was 3.04 with 3.14

Haven't tested overly for robustness, but hope it helps.

Great job Alan!

[adriank]

Scott/Pep, thanks for putting up with my ignorance on my earlier posts on this topic.

The plan will be to go with just a road car setup. So i will be getting 14"x7" rims from Classic Alfa in the UK, and probably running Bridgestone or Pirelli 195/60/14's, hoping these will fit the 7" rim ok.

AK