Tire size options

[TGM]

I'm sure this has been discussed, but wanted to get some input on tire size options for the Europa. The sticker in my 1972 (with the stock 5 1/2 wheels) says 175R13 in front and 185R13 in rear. Correct me if I'm wrong, but no series designation (ie 60, 70, etc), just an R, means 80 series. So, for example, a 175/70-13 would actually be a lower profile tire than a 175R13 (80 series).

My car has 60 series tires on it now (185/60-13) and I think they are too low profile. Where I live (northeast US), there are a lot of potholes and bumps in the road and I generally like to run taller tires. I'm thinking of either 175/70-13 and 185/70-13 or I may go with 185s in the front and 195s in the back. What do you think?

[LotusJoe]

I can't confirm that the old tire sizing of 175R13 implies a 80 series tire. Seems to to me it was a 70 series tire, but I can't find any old reference to confirm that. Coker Tires show classic tires in 13 inch rims as 80 series, so you may well be right. However, the problem is that there simply isn't much to choose from in a 13 inch tire. This is a problem that has existed for a number of years now. I have found about 17 different tires in a 70 series tire, but nothing in a 75 series and only one tire in an 80 series. So your choice my only be a 70 series tire. I'm looking at the Toyo tires for my car but they are quite expensive. An other alternative is a tire by Federal. 

If your willing to compromise to a 70 series there seems to be an adequate selection

[EuropaTC]

They should be 70 series tyres, front & rear. The standard was 155/80 x 13 and the optional alloys/wider tyres were 175/70 x 13 front, 185/70 x 13 rear, which is roughly the same overall diameter as the 155s. The front is technically smaller, but not so much that you'll notice. A  60 series will be smaller and probably means your speedo says you're going faster than you actually are !

If you're interested in the numbers,  from rough calcs the 155/80 has a diameter of  578mm, the 175/70 is 575mm and the 185/70 is 589mm diameter. These diameters are theoretical & will vary between manufacturers to some extent, but 5mm (radius) extra at the rear isn't going to make a big difference, especially as the calcs are for unladen diameters.  the 185/60 series in contrast is around 552mm, quite a difference.

Brian