In a recent post Vince Capaccio wrote:
>> Well I have been trying to find tires for my 66 MGB with wire wheels and
>> so far have not been able to locate the specified 165 R 14.
And then Shawn Moe wrote:
I never saw any response to Vince's question, so I thought I would pose it
again. I have been lurking in the group for a month or so now, and have the
same situation. I have a wire-wheeled '72 BGT that a PO had installed tires of
2 different sizes. Currently there are two 165-14 Pirelli P3s and two 185-70-14
cheapos. Recently I called all of the local (Kansas City) major tire stores
and found that Pirelli makes a P4 in that size, but nobody stocks it. Yes, I
can order them, but that usually means inflated prices. A couple of years
back, I remember reading in my local club newsletter something about MGB tire
sizes. The author had measured the circumference of several different tires,
and had a recommended a replacement size that was commonly available. Has any
body seen such an article? I have seen ads for 175-14 and 175-70-14 tires.
Has anyone had experiences with these sizes and MGB wire wheels?
To which Doug Mitchell replies:
According to the tire profile generator on my cad system at work,
based on the MGB wire wheel being 4.5 inches wide by 14 inches in
diameter, there is approximately a 2 millemeter difference in diameter
between a 165R75-14 and a 175R70-14 tire. This relationship is based on
the average diameter.
So in answer to your question, a 175R70-14 will replace a 165R75-14 with
no measureable difference in speedometer error. One caveat, while the
diameter is OK, I am not so sure about the width. Although it is only
12 mm (1/2 inch) wider overall, I do not know how much room there is
for the steering. Perhaps a MG person can answer this.
Doug Mitchell - Triumphs forever ;-)
Ford and I have an agreement - I don't speak for Ford and thay don't fire me.
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