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90Q Tire Sizing

The stock tires for my 1988 90Q are 195-60-14 with the stock Ronal aero
wheels (6Jx14). I find the stock tires don't fill the wheel wells from a
diameter perspective (not tire width) so today I bought four 195-70-14

The tires are not installed yet but eyeballing the 195-70-14s might cause
some clearance problems on my pot-holed back-country roads and with
snow/ice buildup in the wheel wells. Uninstalled on rims, they are about
24.75 inches in diameter and  the stock 195-60-14s are about 23.25 inches
in diameter. I have been running 15 inch tires on steel rims for the last
year (24 inches in diameter) with no problems. In fact, I found the shift
points changed for the better with the 185-65-15 inch tires or else I have
a good imagination.

The first question is ......since I'm stuck with the 14 inch Ronals for
now, should I exchange the new tires for 195-65-14 or 185-70-14 or can I go
ahead with the 195-70-14 installation without clearance problems.

The second question is .... am I going to change my gearing (shift points)
by increasing the diameter by .75 inches over the 15inch tires.

The third question is ..... with the larger tire diameter, is the
speedometer running slower than reality (i.e. the Q speedometer should read
64mph to equal a real 60 mph) OR do I have it backwards?

Would appreciate comments/responses


John Holt (1988 90Q)
General Delivery
Highland Grove, Ontario, Canada
K0L 2A0