I called WeatherTech and got dimensions:
Driver's Side:
27.5 " tall
17.75 " wide
18.5 " bottom up to where the mat is trimmed in on the left side.
13 " wide where it is trimmed on the left side.
Passenger's Side:
27.5 " tall
17 " wide
19 " bottom up to where the mat is trimmed in on the right side.
14.5 " wide where it is trimmed on the right side.
This fits okay on the driver side, but awkwardly on the passenger side. I think the fact Spyder is in model name gives it away...it is made for the recent MR2 models.
I googled and found Highland rubber floor mats a decent quality alternative. I called JC Whitney and asked for dimensions but they didn't have them. I decided to try them (SKU ZX474853T). I will see if these fit well.
Highland ALL-WEATHER FRONT FLOOR MATS : JC Whitney: Auto Parts & Accessories