Coker Tire has a lot of the "old school" tire sizes. Here are a couple of 145-R13s, but the aspect ratios are not listed. Pictures look about right. I haven't done biz with Coker, no financial interest either.
If that doesn't work, go over to Yahoo Groups and sign into the Spridget or Bugeye group and ask the question. They're all 13" guys over there. Tirewise.
Ok, I'm going to ask a stupid question so please bear with me. My dad was a fleet mechanic and I grew up under the hood of a car. One of my first toys was a set of wrenches so I am not exactly stupid when it comes to cars. I know what the 145 means, (o.d.) and I know what the 70 means (aspect ratio), and the R means radial (B would mean bias ply) and the 13 is the diameter of the rim. What on God's Green Earth does the 71 mean?
From the chart that Wingnut linked to, it would appear that 71 is about the lowest rating there is, so for all intents and purposes it is irrelevant in this case because nothing you will find will be rated lower than that right? If the tire is rated higher than that it is just gravy.
yeah they go lower, but probably not legal for street use, i have a chart that goes all the way down to 60 and that = a little over 500 pounds.
So far tho still striking out except for the one lead. and that's not good, the firestone cost is more than double than the contential from france shipping included. there has to be someone over here selling tires.
It looks like a 155/70R13 would be a fairly close match, probably close enough you would not notice the difference. a 145/70R13 is 535mm O.D. whereas a 155/70R13 is 550mm O.D. so we are really only talking about a total of 15mm difference in O.D. which works out to be 102% of the circumference. Well within acceptable limits i'd think.
here are a couple more possible size combinations that are probably acceptable:
155/65R13
Diameter 531mm
65 Series
165/65R13
Diameter 544mm
65 Series
135/80R13
Diameter 548mm
80 Series
145/80R13
Diameter 565mm
80 Series
175/60R13
Diameter 540mm
60 Series
185/60R13
Diameter 552mm
60 Series
185/55R13
Diameter 534mm
55 Series
That last one by the way is within one millimeter of being the same OD as a 145/70R13 and is probably about as close as you'll get. BF Goodrich makes a Comp T/A in that size it looks like but it might be difficult to find.