Dont run speedlines, they are crap.
We have to run them in the KA challenge and destroy 2 per rally. even on tarmac we twisted one so badly it pulled the tyre off the rim. Although they do get mega abuse on a rally car, i dont think they are as good as the old compomotives we used to run, and they shoul dlast more than 100 stage miles. (and good old steels, well they are indestructable...)