'58 Chevy 36, 17.5" tires & rims

[GuamPilot]

No doubt these questions have been asked but I'm not getting useful results from the search.

My wife and I just bought our '58 Chevy 36. I did not research the tire size before purchase.

I'm finding very little choice in tires. STA Transport at Coker and Specialty Tires of America at SimpleTire. $800 to $1200 for 4 plus mounting, balance, etc.

I did see a commercial trailer tire for $75 each in 17.5. Not sure that's a viable solution.

What other year and model has the 8 lug rims that fit my '58? Sure would be nice to use a common tire size.

The tires on it have thin tread and are old. I want to make a 1000 mile drive in 2 weeks.

Suggestions? Ideas?

Thanks,

Mike & Carrie