s130 said:

Pirelli P6 185/60 R13 80H were absolutely fine. 185/60x14 you mention would be completely wrong as in going to 14 inch from 13 inch would require a profile drop. Not researched but 185/50 or 185/55 on a 14 inch rim would be more appropriate.

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For what reason would it need a profile drop? Gearing? I`ve not had a problem (I was initially on 185/60 14`s, the difference in acceleration wasnt noticeable, the rubbing was however).

I`ve not tried 185/60 13`s so cant comment, the widest I`ve gone on standard steels was 175/60 13`s.

Based on a standard 135/80 R13 (1714mm) the 185/60 R14 (1815mm) will read 6% lower in MPH. 185/60 R13 (1733mm) will read 1% lower in MPH. I also used 185/55 R13 (1677) reading 2% high. However these tyres were (back then) much more expensive and harder to come by. Bearing in mind the number of tyres I got through 185/60 R13s were the overall best choice over a number of factors.

Besides speedo readings the problem/challenge with the Uno (non turbo) is torque and acceleration. Going 6% longer on rolling distance is a hard pull for the engine. Shorter is much better. The Uno engine is a good little revving engine so higher overall RPM/over revving is not an issue.

s130 said:

Based on a standard 135/80 R13 (1714mm) the 185/60 R14 (1815mm) will read 6% lower in MPH. 185/60 R13 (1733mm) will read 1% lower in MPH. I also used 185/55 R13 (1677) reading 2% high. However these tyres were (back then) much more expensive and harder to come by. Bearing in mind the number of tyres I got through 185/60 R13s were the overall best choice over a number of factors.

Besides speedo readings the problem/challenge with the Uno (non turbo) is torque and acceleration. Going 6% longer on rolling distance is a hard pull for the engine. Shorter is much better. The Uno engine is a good little revving engine so higher overall RPM/over revving is not an issue.

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As I said, 175/65 14`s (1778mm) give a virtually perfect speedo reading (as checked with GPS), under reading by 2mph @ 70, which is pretty much bob-on, & as I said, I have no problems with gearing or a noticeable loss of acceleration.

I do have a set of 13" Uno Turbo Mk2 alloys waiting for me to referb them, I might try 185/60 13`s on them when I do, just to see.

175/65 R14 rolling is 1831mm which is 6.8% long. My Uno speedo was reading a little over 8% high against GPS. Also Fiat speedos of that era read high. As you have found the 175/65 R14s have brought your speedo from reading high to around the true value. For my Uno they would have brought mine down from 8% high to about 1% high.

The Unos in the Fiat Racing Racing & Italian Intermarque Challenge racing series used to run 45 or less profiles on 13 inch rims to give them better pick-up and acceleration PLUS an overall lower centre of gravity. The Uno is naturally a narrow track top heavy car with all those large windows so a lot of effort and experimenting was done to improve this.