Hi
There isn't a cheap option. generally speaking cars don't have tyres that are this tall and this high performance.
A 205VR15 tyre should be about 710mm tall (or the gearing, fuel economy, speedo, clearance under the car & appearance will be wrong). this is about the same diameter as the 16" tyres that were fitted to earlier cars.
It's funny; nearly all the best cars of the 40's and 50's fitted either 600X16 crossply or 185VR16 radial tyres with a diameter of about 700mm - 710mm. cars such as Bristol, XK Jaguars, Feltham Aston Martins, Ferrari 250, Maserati 3500GT, Pegaso, Jensen 541.
Then in 1964 Pirelli developed the ability to make a radial tyre of the same diameter 700mm - 710mm but fitted to a 15" wheel with a bigger section and still able to withstand speeds of up to 150mph and they were adopted by Ferrari 330 & 500, Lamborghini 350GT, 400GT, Espada & Muira, ISO Griffo & Rivolta, Maserati Mistral, Ghibli, Sebring Aston Martin DB6 & DBS, etc and this size was also adopted by Bristol (though i am not certain what make)
Then in 1968 the tyre size 215/70VR15 took over, but this is smaller in diameter and wider It could also do with wider wheels to gain the benefit.
I would suggest your cars will be better on the 205VR15 Cinturato CN72
https://www.borrani.com/pirelli-tyre...cinturato.html
In case someone doesn't undersstan how tyre sizes work i will try to explain
215/70VR15
215mm wide at the widest part of the tyre (no tread width)
70 = (the aspect ratio) 70% of 215mm is the height of the side wall (150mm)
V is a speed rating meaning 150mph
R means radial
15 means to fit a 15" wheel
Overall diameter = 380mm (15") + 150mm + 150mm = 680mm
205VR15
215mm wide at the widest part of the tyre (no tread width)
aspect ratio - because when radial tyres were first invented there was no choice of aspect ratio so they did not mention it in the tyres description and the standard was 80%. so 80% of 205mm is the height of the side wall 164mm
V is a speed rating meaning 150mph
R means radial
15 means to fit a 15" wheel
Overall diameter = 380mm (15") + 164mm + 164mm = 708mm
185VR16
185mm wide at the widest part of the tyre (no tread width)
aspect ratio - because when radial tyres were first invented there was no choice of aspect ratio so they did not mention it in the tyres description and the standard was 80%. so 80% of 185mm is the height of the side wall 148mm
V is a speed rating meaning 150mph
R means radial
16 means to fit a 16" wheel
Overall diameter = 405mm (16") + 148mm + 148mm = 701mm
I hope this will explain why the cars loook silly when they are fitted with tyres like a 205/70VR15 because it will be nearly an inch smaller in radius, and leave the wheel arches empty, with less clearance under the car, all the gearing and speedo wioll be wrong etc.
Good quality unusual sized tyres are not cheap, but they do make a difference. today many of thyese cars are fitted with 215/70VR15 Avoon CR6 ZZ tyres which are great on the race track and are the cheapest branded tyre in the size but the carcase is too harsh for these cars and they won't last. i say stick with the good stuff and fit Cinturato
Dougal
Longstone Tyres