How much of a hit can I expect to get from ultra high performance summer tires?

That is the idea of the coolant being stored in the thermos, is it not? Hal

 

It is but I have read that the car still goes through its warming stages regardless. I could be wrong on this though.

 

I experienced a significant mileage drop when the dealer installed non LLR tires on my 2009 Touring. When I replaced them with Bridgestone Ecopias the mileage improved dramatically.

Here is the thread on my experience with tires on the Prius.

http://priuschat.com/forums/gen-ii-...0-yokohama-avid-envigor-gas-milease-drop.html

 

Yeah. It still seems to, although maybe not for the full 56 seconds after ICE ignition. I think the engine already being warm and the thermos helps.

Today, IIRC, FWT was above 180 F, I had to stop and power down. I came back out a few minutes later to power back up and go. FWT was still up there but I saw it going thru stage 1a (negative IGN values).

 

Oh, that is interesting! So I guess there is a bit of a hit.

 

It's probably a minor hit but do it enough times and it could add up to a big hit. It's worth checking out.

 

Now imagine what you would have got with LRR tires of the appropriate size.

 

Here is what 101Tires.com shows for the size difference.