I would completely agree with normal sized Mini suitable tires Ian.
the reason i questioned the tyre size is looking at the posters picture the wheel arches have had a lot more metal removed than usual and the front flare is sitting way higher than usual so he is either running taller tires with maybe a beam axle in the rear for clearance or it is slammed.
Of course it could be fitted with 50 series tires and he just likes that stance and as you stated that is not an issue with the small amount of difference but if he is running larger profile tyres it needs consideration in determining a FD ratio.

Steve:
     On my charts I do not see a 4.5 CWP combination listed.  I do see a 4.35 (15/65), 4.666 (no information), and a 4.90 (11/54).  My collection of CWP goes from 2.95 to 3.938 with 3.265 and 3.44, in the middle.  

I think we may be overlooking a couple of things here. Are you using your speedo or a GPS to determine speed? What kind of tach are you using? My chart has 4.35 CWP at 71MPH at 5500 RPM. That's 13.06 MPH at 1000 RPM.

Also, there are factory OD drop gears both primary as well as first motion input. 

A while back someone posted a 4.5 CWP in the for sale section. I can't seem to find it now but would like to see what became of it. I never had one in my collection. It would be neat to have one. Steve (CTR)  

The maths are not too complicated... but the answers they throw up are pretty screwed...

Ignoring the tyre size ..which does have an effect but not too much... 60mph @5500 gives something a bit under 11 mph/thousand revs.  A 4.27 diff (which was a factory option for the S back in the day) will give something like 13 mph/K-revs (according to my factory manual). You’re looking for something more like a 2.95.  I don’t have numbers for that but a 3.1 gives 18.1 mph/K-revs (on 165/70 tyres).... ie 55mph at 3K revs.  Any Mini will pull 4K quite happily all day every day and that’s the equivalent of 72mph...

My guess is that you have an Austin America engine and box.  AAs ran 12” wheels (without low profile tyres) so used 4.something diffs.  Installed in a Mini this would give something like the mph/revs figures you are quoting.

You can change the mph/revs numbers using non standard drop gears but these are aftermarket parts and I have never looked at any price/reliability issues.  Alternative diff ratios are available new or second hand and are no big deal to fit (once you get the engine out of the car 

Go have a look at Guess-works website.  They specialise in Mini gearboxes and give a whole bunch of numbers for speed vs revs for a wide variety of final drive and gearbox ratios....

Cheers, Ian

Also your wheel tire size needs to be factored in as by the picture it looks like you are using 13's with maybe a taller than 50 series profile.

Wow..... 5500 @ 100 k is high.  You must be running a 3.67 or lower FD.

I have an 1130 with a 3.1 FD and sit around 3600 @ 100.  I had a pick up that I drove from SK to BC with a 3.1, it was great.
with a 3.1 you still have plenty of get up and go in town.

A 3.44 ( the most common ) would put you around 4000 rpm @ 100

Changing the FD is an engine out job btw.

I do a little tranny work and while math is not my strong point I did a chart for gear ratios vs RPM. It covers overall final drive ratios from 2.55 to 4.35. I don't have a ratio that matches your numbers. My 4.35 comes out at 71/72 mph at 5500. A 2.95 shows 57 mph at 3000 and 2.76 is 61 at 3000 RPM. There are OD drop gears that allow you to fine tune these numbers. 

I currently run a 1360 Cooper S with a rod change extra wide ratio gears set and a 2.76 with both OD drops for a 2.55 overall ratio. Each gear change is a 1000 RPM drop so torque is required. Third gear is the same ratio as a std. 3.44 final drive. Under 45 mph I use third and rarely shift to fourth below 50 MPH. It does not produce good MPG figures but is pleasant rolling 70 MPH at 3000 RPM. 

I ran a 998 with a 295 and while no hot rod I did like the ratio. I also have a 998 with a 3.1 CWP and it almost makes 50 MPG every tank. 

I have a 998 in the works A+ with flat top pistons, press fit rods, ultra light flywheel and Cooper S balancer. Mildly ported 295 cyl. head, hard seats, and O/S valves. Twin 1 1/4 SUs and Maniflow simple Cooper style header. 

The tranny plan is a Rod change with S close ratios and a 3.2 CWP. Steve (CTR) 

Final drive ratio is the best way to achieve your goal. Depending on the size of your tires, I think you would need the 2.76:1 FD to come close to what your're looking for (presumably in 4th gear.) 

To pull a FD that tall (lower numerically) your motor will need to produce plenty of mid-range torque. So it's good you have a 1330. If you have a high-revving racy cam that produces its power up high and not much in the low-to-mid range, it might not be very happy saddled to a 2.76 FD.

The other alternative is a 5-speed, with an overdrive 5th. The priciest answer to this question.

Hello

I have a technical question about the mini transmission.  I have a 1979 mini 1330cc with a stock 4 speed transmission.  I find at 100kph(60mph) the engine is at 5500rpm. I was wondering if someone could advise me on parts I might need to change the gearing ratios so it more like 3000rpm cursing at 100kph (60mph).  does anyone have advice on what I should change?  Final Drive ratio? gears?

Thanks
Tom