205/50-15 vs 245/40-17 RE71R?
 

Has anyone tested these two tires against one another or an RS4 for endurance racing?

205/50-15 vs 245/40-17 RE71R

We've been running the 245/40-15 RS4 and we get a few races out of them. We know that the 205 RE71Rs will burn up fairly quick (3-4 stints.). We've also heard anecdotally that they're about a second a lap faster, however we assumed that was apples to apples in tread width. We didn't find any testing of the 245/40-15 RS4 versus the 205 RE71R.

All all of our rims are 15x9s 15x9.5s or 15x10s. But we've bit the bullet and I bought a set of 15x7.5s and 17x9s along with the appropriate RE71Rs.

We plan to test them in October but I was hoping someone had already done some of the leg work so We can get a jump on testing.
https://cimg8.ibsrv.net/gimg/www.mia...11df59b05b.jpg


I know Ryan is running the 285/30-18 but we only have about 147rwhp and I think the aero penalty would be too great. He had a set of the 285/30-18s in the RS4 compound to test out but the 18" rim was just too difficult and I ended up giving them away to a Camaro team.
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Any insight would be appreciated.
https://cimg1.ibsrv.net/gimg/www.mia...b7b9b878ba.jpg