I have a car that is potentially capable of 140 mph + and in the past I was able to get VR rated tyres for my 13" rims but after a quick search it looks as if they are no longer available. The car I have has Min sub frame A+ engine suspension etc and I have a choice of 10" alloy 12" steel !3" alloy wheels. Having a light car makes the unsprung weight important, with less sprung weight for the springs to push against the unsprung weight needs to be lower. The 10" wheels are my lightest so choosing these seem a good option with either 145 or 165 tyres. However the 12" rims would be better suited for the overall gear ratio and would look ok without wheel arch mods.
My 13" wheels look good but it looks like 175 is the only choice I would have. 145's have an aerodynamic advantage giving better economy and high speed acceleration. The speed rating is based upon temperature range, so 10" wheels would heat up more although the ratings are based upon a heavier load I expect. Stiff side walls are important on the rear tyre as it is a three wheeler with one wheel at the rear. Any advice would be very welcome.