I currently have to replace my rear potenza re070's and am wondering if I should replace them with the same ones or to switch to re-11's.
The fronts are re070's with about 75% tread left. I know mixing tires is not recommended but I'm wondering if this would be ok since the re-11's are a better tire.
I do about a dozen track days a year so if any experienced track guys could chime in I would appreciate it!
Thanks

 

If you were installing a comparable category tire with the RE070 in the rear, I'd say yes.

But because your choice is RE-11, I would recommend installing all 4, and selling the fronts.

 

I would buy any tire in that category for the rear (re-11, ad08, star spec... ect) and run your same RE070 fronts until you kill them. The balance will change from what it was but it wont be significant and you'll get used to it after the fist session or two. As a bonus you will save some money since RE070 are not cheap, especially considering they're an old compound that has been passed by the newer generation of "extreme" perfomance summer tires

 

Its not recommended but you'll be ok. You're likely experience some understeer as your rear tires have more grip than the front. If it was the opposite, I'd say no since that can get a little iffy.