I used to use Streetmaps but now Iβve got full OS maps on my phone & Ipad which I use for off-road cycling routes, both 1:50.000 & 1:25.000.If you're not already aware Streetmap allows the 1:50.000 OS maps to be viewed which shows road widths and gradients - as well as other higher and lower scales.
Still my fault for not checking.