So, would I be totally crazy to consider finding some light 14" alloys and putting Bridgestone B381s on the Prius? It seems like their rolling resistance is a good 30-40% lower than anything I'm currently considering in a 15" (namely X-radials and ContiProContacts). BTW, I am not really counting wet/snow handling too high, as we get ~7" of rain per year so Hydroedges and the like aren't really in the running at the moment. The biggest problem I see is the lack of wheels. Not a lot of demand for 14" rims these days The 5x100 bolt pattern makes it even worse. At least some 14s are available for the Miata and Civics, but they are a 4x100 pattern. Adapters seem expensive, and would add weight. The 5x100 puts us in the dubious company of the Pontiac Fiero and Dodge Neon. Even the Neon crowd are only shopping for 17s these days by the looks of things. There is a set of stock Fiero alloys on ebay right now.... Only other real option I have found are Enkei rally wheels ordered from Japan or Superlite racing wheels from UK. Either way, we're talking at least $200-300 each but it does get you in the <10 lb territory. Those fiero wheels are starting to sound pretty good Rob
The tire in question is only made in one size, at a 14" wheel diameter. Its geometry is such that its outer diameter, and hence revs/mile are almost exactly the same as the Prius' oem tire. Tire Specs for Bridgestone B381 I believe they are the oem tire on the honda civic hybrid and gx natural gas models. The oem goodyears, X-radials and contiprocontacts are probably in the ~0.009 range for RR, hydroedges probably 0.010. The B381s are 0.0062-0.0065 depending on whose data you look at. Numbers I've seen from various studies estimate ~1-2% better mpg for 10% lower RR, another study was ~3-5% for 20%. Theoretically, you could see 6-10% better mpg over the hydroedges, or maybe 5-8% over the oem tires. At 50 mpg we could be talking a real 3-5mpg here. If the wheel/tire combined weight was also signifigantly reduced, their could be additional benefits. You'd probably need some of those 9 lb racing wheels to test that one though. Not sure I want to be the guinea pig riding around on fiero wheels to find out if these tires are all they're cracked up to be Rob
