$${T_t = \frac{bg(M + \frac{1}{2}m)}{a} \\ = \frac{(9,8\, \mathrm{m/s^2})(2,5\, \mathrm{m})(430\, \mathrm{kg} + 85/2\, \mathrm{kg})}{1,9\, \mathrm{m}} \\ = 6093\, \mathrm{N} \approx \underline{\underline{6100\, \mathrm{N}}}}$$