A guide to the wheel sizes for the 'Book' Locost based upon Mk2 Ford Escort

This is still a work in progress. I would welcome other info and photos.

Disclaimer: These are my own personal experiences with wheel fitment, I accept no responsibility regarding the correct fitment to your own vehicle. Please consult the wheel supplier for further information on suitability of fitment.

Alloy Wheels.

First and foremost we must look back at the original fitment of alloy wheels to the Ford Escort Mk2 Ghia and Sport range.
The standard RS type alloy wheels were 6J x 13 with ET19 offset, 108 PCD and fitted with 175mm section by 70 profile tyres. (There are 5.5J versions available as well as much wider competition variants, I've come across 8.5 !)

It is important to note that this gave an overall diameter of wheel/tyre of approx. 23 inches and an offset of 19mm from the wheel centre line to the hub mounting face. This offset will give approx 6mm tyrewall clearance from the rear trailing arms.

ET Wheels have a mounting offset from centre known as ET (German= Einpress Tiefe, literally meaning "push in depth").
If the wheel rear mounting flange is in a centre line to the wheel rim it has zero offset. If the flange is further forward from rim centre line then it's a positive ET, if it's back it's a negative ET. So given the Ford example ET19, then the flange is 19mm forwards from the wheel rim centre line. You can see from this that it is possible to play with the available offsets to help with tyre clearances when fitting wider wheels on a modified car. If the offset is not available then that's when spacers come into play, hence if you need a ET38 offset you would use ET35 and a 3mm spacer with longer studs.

'J' is the wheel rim depth at edge. It's what prevents the tyre from rolling off the rim in hard cornering. It's a deeper rim used on wider wheels, there are other alphabet letters but they are usually rare.

PCD(Pitch circle diameter) this means the distance between adjacent mounting holes. In the case of Ford they are 100 and 108mm 5 and 4 stud holes. Others are out there, Fiat are 98mm, BMW's use a range of 4 stud early years and 5 stud later.

This information can usually be found cast in figures on the rear of the alloy.

Later model 'Capri Laser' wheels are to all intents the same as the RS except for the wheel nut fastenings and the rim around the wheel nut holes being thicker material.

Ghia type wheel as fitted to some Capris etc.

The overall gearing of a Mk2 was set by the following factors:-

Wheel overall diameter
Final drive ratio
Gearbox ratios.

Changing any one of these changes the gearing for the vehicle. Thus to keep the overall gearing the same we must try to keep a wheel diameter of 23 inches. This will ensure the same overall gearing and keep the speedometer reading correct.

A common problem is that Laser type wheels are obtained and modern low profile tyres of say 185/60 are fitted to them.
This achieves a wheel/tyre diameter of 21.5 inches, which immediately lowers the overall gearing of the car. Incidentally it also lowers the car and reduces the under car ground clearance! Not good for sumps!!

If you want to lower the gearing then I suggest you change the final drive ratio.

New Wheels

A problem I came across when wanting to replace my wheels with another more modern type was the lack of 6J width wheels. Modern replacement wheels are available in 6.5J. Not a problem if you are in the building stage, but a problem for me when I have the narrow pattern arches at 240mm wide and smaller width front cycle wings.

13 inch wheels although still available, meant the fitment of 70 profile older tyres in order to keep the diameter to as near as 23 inch.

I therefore had the choice, either 14 inch with 60 profile tyres or 15 inch with 50 profile. Both of which kept the diameter close to 23 inch.

I finally chose the 15 inch wheels, mostly due to the relatively cheap cost and choice of the 195/50 tyres

It is possible to use 6.5J x 15 inch wheels with 205/50 tyres and achieve a 23 inch diameter but the cost of the tyres is significantly more. I also could not get them under the narrow pattern rear wheel arches.

Secondhand wheels

The standard offset for the Locost is 19mm but it is possible to obtain on the secondhand market, Peugeot 205 FWD wheels with an offset of ET18. These are a direct fit and are quite cheap from various sources such as Free Ads etc.

There are a number of FWD Ford wheels about. Unfortunately these have an offset between ET35 and ET45. They will fit the wheel stud but not into the arches as they are set much further in.
It is possible to fit them if you are willing to fit up to 25mm spacers to the hubs along with extended wheel studs. I personally would not recommend them due to problems with wheel location, stud failure, bearing wear etc.

Wheel studs and wheel nuts.

It is important to obtain the correct wheel nuts when attempting to fit alloy wheels to the wheel studs. It is also important to make sure the wheel studs are of the correct length for the wheel. Approximately 8 turns are required for a correct fit of nut to stud.
For Fords, a simple upgrade if you require longer studs is to use Sierra wheel studs which are available for around a pound each from various sources, including Ford dealers.

Fords use three different nuts on alloy wheels I believe, (there may be older variants). The difference is flange nuts and cone nuts. Flange nuts usually have a large washer fitted and tighten onto a flat area around hole. Cone nuts use a chamfered nut into a chamfered hole. Standard on all factory wheels but some aftermarket wheels supply their own wheel nuts with a different cone taper angle. It's worth checking when buying s/h wheels, it may cost as much as a single wheel just for a complete set of nuts. The 'loose' cone nuts as used on the Laser wheels are still in use today on Mondeo's etc.

Steel Wheels

Discounting 12 inch wheels, there were various steel wheels as fitted to the Mk2 range but usually the size was 4.5 x 13 with 155/70 tyres. These should pose no problem with fitment to a Locost.

Important info on tyre balancing courtesy of Yokohama Tyres

To facilitate proper balancing, Yokohama places red and yellow marks on the sidewalls of its tires to enable the best possible match-mounting of the tire/wheel assembly. There are two methods of match-mounting Yokohama tires to wheel assemblies using these red or yellow marks:

Weight (yellow mark)
Uniformity (red mark)

Weight Method

When performing weight match-mounting, the yellow mark on the tire, indicating the point of lightest weight, should be aligned with the valve stem on the wheel assembly, which represents the heaviest weight point of the wheel assembly. After match-mounting by either of the above methods, the tire/wheel assembly can be balanced.

Uniformity Method

When performing uniformity match-mounting, the red mark on the tire, indicating the point of maximum radial force variation, should be aligned with the wheel assembly's point of minimum radial run-out, which is generally indicated by a colored dot or a notch somewhere on the wheel assembly (consult manufacturer for details). Radial force variation is the fluctuation in the force that appears in the rotating axis of a tire when a specific load is applied and the tire rotated at a specific speed. It is necessary to minimize radial force variation to ensure trouble-free installation and operation. Not all wheel assemblies indicate the point of minimum radial run-out, rendering uniformity match-mounting sometimes impossible. If the point of minimum radial run-out is not indicated on a wheel assembly, the weight method of match-mounting should be used instead.

When I bought my new wheels and tyres I had problems with the balancing, the wheels requiring lots of stick on lead weights.
Thanks to the above info I was able to take them back to the depot and insist they be weight matched using the coloured dots on the tyres. They then only required minimum lead weights.
The tyre fitter had no idea of this requirement and was in fact very pleased to get the info. He had been trying to balance many a wheel set and was wondering why some would not balance properly.
He readily admitted that the turnover in staff meant proper training was never given, ah well!

Further Info
This link will take you to an excellent site with extensive info on wheels and tyres :-
Wheel and Tyre Bible