Motor Trend got a Chevy Bolt for a long term test and one of the first things they noticed was lots of tire squeal and understeering when pressed hard in the corners - Sound familiar?? Since they were going to have the car for a year, somebody talked them into putting a set of summer tires on in place of the OE Michelin LRR tires for a couple months
As expected, most every measurable handling parameter showed marked improvement - Braking, cornering (understeer was almost completely gone!) slalom and lateral acceleration (skidpad) tests were all much better. Since the Bolt's power train is programmed not to spin the OE tires under straight line acceleration, 0 to 60 and quarter mile times were unaffected
What *shocked* everybody though was the 'price' you pay for all the improvement. They used sophisticated test equipment to measure mpg-e with both the OEM tires and the BF Goodrich UHP summer tires and the numbers were almost not believable. Chevy claims 119 mpg-e and their tests with the Michelins showed 122.2. When they tested with the summer tires, they had to double check all their measurements before they believed what they were seeing - The summer tires dropped it 27%, down to 89.2 mpg-e which changes the cars range by a like amount. Chevy claims 238, they tested it at 243 with OE tires but only 178 miles with the summer tires!!!
Our iMiEV's understeer something terrible with the stock LRR tires - I always figured it was due to the fact that they kept the tiny front tires the gas version of the car used, despite the fact that the battery made it a much heavier car, with more of the weight on the front tires than the lighter gas version, but it looks like it may be the LRR tires which are the bigger part of the problem . . . . . but I'm not *quite* ready to give away 27% of our modest range to solve it - Back to going slower around the cloverleafs!