XR2i Wheels

I’ve bought some XR2i wheels wearing 185/60/13 tyres - precisely the tyre size I was looking for.

The XR2i

For those of you who know your mark three Fiestas, you’ll know that the offset on the XR2i wheels is approximately 30. From the FAKQ on wheels and tyres, this means that the wheels will be protruding approximately quarter of an inch (each side of course) from their standard location.

And the wheels are also wider by half an inch, although this should only make a quarter inch difference to the outside.

The effect of this is that we’ve increased Kermit’s track by an inch front and rear.

Why 185/60s on a 13” Rim?

These tyres are a little bit wider than the standard Ka wheels (5½J rather than 5J), but have the same profile (60). As you can read from the FAKQ, since the profile is an expression of the height (diameter) of the tyre, relative to the width, the 185/60 will effectively be a “fatter” profile compared to the 165/60 tyres. The overall wheel diameter will be very close.

However, with more rubber and less wheel, the Ka’s ride is slightly softer on 185/60/13s compared to 165/60/14s, which is going to be advantageous for a significant proportion of my new commuting route (which is over rough road surfaces). However, the advantage of the 185 width tyres is that it should provide for better potential grip, traction and braking under some circumstances.

When it is very wet, or in wintry conditions, the reduced pressure on the road can reduce grip. Now Kas on 195/45/15s are especially sensitive in icy conditions - my hope is that the Ka will be easier to handle on 185/60/13.

The difference between 165/60/14s and 185/60/13s depends very much on the tyres used on the wheels. With the original Wynstar tyres, I was wanting the Firestones on the 14” alloys back!

One of the concerns that I had about using 185/60s was the potential for tyre sidewall deformation. This is a phenomena that occurs when the cornering load is so high the tyre flops about on the rim, causing all sorts of handling problems. After extensive testing <cough> it is possible to overwhelm the tyre sidewalls if the pressure is too low. With the Falkens in the dry, if the pressure drops below around 31 PSI front or rear, you can overload the tyre through cornering so as to cause sidewall deformation.

One significant advantage of using 185/60/13 tyres is that there is a much wider choice of tyres available.

Style

I wasn’t convinced that I’d like the XR2i wheels, but having had them on the lad for a bit I’ve grown used to them. In some respects, using 185/55 profile tyres might look a bit better but this would be detrimental to his ride. Therein is the compromise we’ve made!

The Results

In summary, there’s a worthwhile improvement in Kermy’s dynamics. The wider track gives him an effective lower centre of gravity, which in turn improves his resistance to body roll. When combined with the Ford Racing Suspension and the strut brace, the result is a comparable ride to the standard machine on 165/60/14s but rather sharper handling.

At low speeds, the only difference is that the ride is smoother. It’s more obvious when going over speed bumps and mid depth pot holes, where the lad feels rather more supple.

As the speeds notch up, the difference is most obvious when cornering. Turn-in at all speeds feels slightly sharper, helped by the strut brace and Ford Racing suspension, but if you’ve let the front tyre pressures drop below 31 PSI and you’re abrupt with the steering there is a lurch during turn-in as the sidewall absorbing the load.

In Conclusion

To conclude, perhaps Ford should have used 5½J 13” rims and 185/60s as standard?

In isolation, these wheels improve the Ka’s dynamics. The wider track and improved grip (subject to tyres) is a worthwhile upgrade.

When combined with the Ford Racing Suspension and strut brace, the result is a Ka that rides just as well as the standard machine on 14” alloys (if not slightly better) but improves on everything about the Ka’s handling that makes it such good fun.