This Morgan original had 165-R15 Radial tyres on 72 spoke 5" wire wheels.
In 2001 I changed to Bridgestone tyres 185x65-R15 and
extended the rear wings with some 15mm.
With the turbo power, the grip was not good so further extension was
needed.
I got 6" 72 spoke wire wheels and decided for what I found the best tyre
for the purpose, Continental Premium Contact 2 in 215x60 R15. It give
+2,82% on the speed to RPM. Normally you should stay within +/- 2,5%,
but longer gearing was preferred.
In this configuration the rear wings should be further extended with
2x30mm. As you can see on the pictures this requires a lot of extra
work: Welding extensions, filling old holes, a lot of fairing and
painting.
Over all the result was beautiful and worth the work.
|
Wire wheels |
Circumreference |
Speed |
Speed |
Diff |
|
Tyres |
mm |
5g 3000RPM |
5g 6500RPM |
|
|
185x65 R15 - 5" |
1952,5 |
104,5 km/h |
226,5 km/h |
0 |
|
215x60 R15 - 6" |
2007,5 |
107,5 km/h |
232,9 km/h |
+ 2,82% |
Simulations show that even with a drag coefficient of
0,68 'as open' (its like a bus) there should be enough power to reach a
top speed of 232,9 km/h (145,5 mph). It is not tested and of no
interests.
Tyre Size Calculator:
http://www.alloywheels.com/tyrecalc.asp
Rear end before
Rear end after |
|
Before extending rear wings |
Wide wheel, rear extended |
Before sheet metal work, fairing and painting |
