First, one engine's mass can be amortized over multiple cars trained together.  Also the rolling friction of a steel wheel on a steel rail is significantly lower than that of rubber tires on pavement.  Finally your load capacity is much higher.

Most of the benefits are accrued at scale.

But, yes, the cost of tires — including the environmental costs of manufacturing and distribution and the labor costs of installation/replacement are significantly higher for rubber due to their much shorter operational lifespans.

Basically, the tradeoffs are all: higher capital investment (infrastructure and materials) vs. operational expenses and flexibility.