
...You can't change the tyres... Assuming your racing a Formula GT car, that is.
Other than that, If you you want to conquer it in B-Spec, like Mr.OzzyGT said, you'l have to change the pace setting according to the corner. Unfortunately this means you'll have to baby sit & spoon feed poor Bob/Bobette who can't help playing in the sand or the dog **** that litters the traps for the entire race.
All the drivers, not just Bob, tend to come off the track on the
second before last turn before the pit straight. This means you can possibly
lose 10 seconds and a lead before you know it. What I would recommend is doing speed 4 up until the downhill chicane then put it to 3 just before that. After the chicane put it down to 2 on the corner I mentioned above then up to 5 for the straight and 4 for the bit after the straight up till the chicane.
If your B-spec pal doesn't have more than 6000 points, it could be a bit more challenging (In that case, do it in A-Spec). Once you get the hang of it though, it'll be a breeze.
Hope this helps,
FormulaGT