Technical Tire Size

[mm3snipe]

I have a 79 spider with the factory 13 inch rims and want to get a different size tire than the 1658013 that I have on it now, are there any alternative to this size without going to a 14 inch rim. Thanks in advance.
steve

 

[Caravadossi]

I have a 79 spider with the factory 13 inch rims and want to get a different size tire than the 1658013 that I have on it now, are there any alternative to this size without going to a 14 inch rim. Thanks in advance.
steve

If you’re currently running on 165/80R13, & given the alternative spec is 185/60R14(?) - then surely any tyre that stays within those dimensions will fit.

One example: 185/70R13.

165/80R13 wall: 5.2” rad: 11.7” dia: 23.4” circ: 73.5” revs: 862
185/70R13 wall: 5.1” rad: 11.6” dia: 23.2” circ: 72.9” revs: 869
185/60R14 wall: 4.4” rad: 11.4” dia: 22.7” circ: 71.4” revs: 887
(Source: Miata tirecalc)

Have a play with a tyre calc application - & let us know your results.