| Round Rock to Popovo | 6,221.00 mi (10,011.73 km) |
| Round Rock to Provadia | 6,271.97 mi (10,093.77 km) |
| Round Rock to Radnevo | 6,260.74 mi (10,075.69 km) |
| Round Rock to Radomir | 6,137.92 mi (9,878.02 km) |
| Round Rock to Rakitovo | 6,207.09 mi (9,989.34 km) |
| Round Rock to Rakovski | 6,225.61 mi (10,019.15 km) |
| Round Rock to Razgrad | 6,222.28 mi (10,013.79 km) |
| Round Rock to Razlog | 6,188.48 mi (9,959.39 km) |
| Round Rock to Ruse | 6,188.17 mi (9,958.90 km) |
| Round Rock to Samokov | 6,170.64 mi (9,930.68 km) |
| Round Rock to Sandanski | 6,196.15 mi (9,971.75 km) |
| Round Rock to Sevlievo | 6,195.96 mi (9,971.44 km) |
| Round Rock to Shumen | 6,249.29 mi (10,057.27 km) |
| Round Rock to Silistra | 6,220.15 mi (10,010.37 km) |
| Round Rock to Sliven | 6,256.84 mi (10,069.40 km) |
