22T rear minispike...........what insert?

[Shaun_TLR]

Using yellow minispikes for the rear on grass and astroturf, what insert do people suggest?

I use medium for the buggies I own, but never renewed tyres on truck thus far

ta

[Kelk]

Shaun I haven't been on grass but I use these most of the time: http://www.modelsport.co.uk/?product_id=38895