ClimateMaster T27 - 5 ton unit (064), no aux heat. 
Install manual says 60 amp breaker and 6 gauge wire.

Is that correct with no aux heat?

Seems excessive to me.

Thanks in advance.

Just for comparison, my 4T GeoMax 2 (ClimateMaster) says 50 amp breaker and it's wired up with 8 gauge copper wire (220 VAC). The Aux Heat strips are on their own circuits, with the 10 KW stage on 6 gauge, and the extra 5 KW stage on 10 gauge. 60 amp breakers with gauge 6 sounds about right. I think my wires have a smaller ground (something like 8 gauge with 10 ga. ground) but the wire is correct.

Absolutely go with #6 wire. Min circuit ampacity is listed on unit nameplate as well as max overcurrent protection.

Heavier guage wire helps avoid voltage dips during compressor starts - compressor briefly draws the amperage shown under "LRA" (Locked Rotor Amps) upon every start. Beefier wire combats this effect.

min amps ~43 would permit smaller wire, but dips and long run times can really heat it up.
recommended wire from CM would not prevent an inspector from passing you if you used 8 wire and 45A fuses.
j

But why set the stage for needing a hard start kit a few years down the road?

Thanks everyone, will go with CM recommendation, the run is only about 10 feet.

In that case 8 is probably OK.