Anaconda have a low speed rating which is the same for each tyre size, the Insa Turbo Special Tracks have a higher speeding which varies from size to size.

Greenway Anaconda

Tyre Size: 235/85R16
Load Index: 114
Speed Rating: K

Tyre Size: 265/75R16
Load Index: 114
Speed Rating: K

K = 68.4 mph

(source C-TYRES tyres website)

INSA TURBO SPECIAL TRACK

Tyre Size: 265/75R16
Load Index: 112
Speed Rating: Q

Q = 99 mph

Tyre Size: 205/80 R16
Load Index: 100
Speed Rating: S

S = 112 mph

Tyre Size: 235/85 R16
Load Index: 120
Speed Rating: N

N = 87 mph

(Source www.4site4x4.co.uk)