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JSH · 04-26-2022, 05:15 PM

A little update:

The range has been slowly growing but I was curious how much I was throwing off the car by running undersized tires. Does the car pull speed from the speedometer, GPS, or both? I assume the speedometer.

My winter tires are Bridgestone Blizzak sized 185/65R15 with a diameter of 24.5 inches and 852 RPM. Stock tires for the Bolt are Michelin Energy Saver A/S sized 215/50R17 with a diameter of 25.5 and RPM of 815. So the tires are 4% smaller and the car thinks it is going 4% farther than it actually is.

I have no answer on this yet - the car will take some time to adapt.

What I did notice right away is that the stock wheel / tire combo is HEAVY. I could easily tell the difference when swapping wheels. The stock wheel / tire weights 44 lbs even with the tread worn down almost to the wear bars. The 15" wheels / winter tires weigh 34.9 lbs. So 9 lbs lighter - likely 10 lbs lighter with full tread.

WHY do automakers put such heavy and oversize wheels on their vehicles? I know the answer - big is in style but the penalty for that style is less efficiency, poor ride, and expensive tires when it is time to replace them.

Part of that weight is Chevy deciding to remove the spare from the Bolt and instead having Michelin put a layer of tar on the inside of the tires to self seal small punctures. That adds a pound per tire vs the regular version. Just the tire is 23 lbs while the Blizzak weighs 18 lbs.

I'll be shopping for replacement summer tires. I won't be buying another set of stock tires. They are crap with a BB rating for performance and temperature. Feel on the road matches that poor rating.

Since everyone has been talking about fuel prices lately: My wife has been driving the Bolt for her 50 mile commute since I've been travelling. To date we have spent $28.67 on electricity. It is pretty crazy that we bought here a car to replace the TDI on April 4th and she didn't drive it until yesterday.

04-26-2022, 05:15 PM	#34 (permalink)
JSH AKA - Jason Join Date: May 2009 Location: PDX Posts: 3,599 Adventure Seeker - '04 Chevy Astro - Campervan 90 day: 17.3 mpg (US) Thanks: 325 Thanked 2,146 Times in 1,453 Posts	A little update: The range has been slowly growing but I was curious how much I was throwing off the car by running undersized tires. Does the car pull speed from the speedometer, GPS, or both? I assume the speedometer. My winter tires are Bridgestone Blizzak sized 185/65R15 with a diameter of 24.5 inches and 852 RPM. Stock tires for the Bolt are Michelin Energy Saver A/S sized 215/50R17 with a diameter of 25.5 and RPM of 815. So the tires are 4% smaller and the car thinks it is going 4% farther than it actually is. I have no answer on this yet - the car will take some time to adapt. What I did notice right away is that the stock wheel / tire combo is HEAVY. I could easily tell the difference when swapping wheels. The stock wheel / tire weights 44 lbs even with the tread worn down almost to the wear bars. The 15" wheels / winter tires weigh 34.9 lbs. So 9 lbs lighter - likely 10 lbs lighter with full tread. WHY do automakers put such heavy and oversize wheels on their vehicles? I know the answer - big is in style but the penalty for that style is less efficiency, poor ride, and expensive tires when it is time to replace them. Part of that weight is Chevy deciding to remove the spare from the Bolt and instead having Michelin put a layer of tar on the inside of the tires to self seal small punctures. That adds a pound per tire vs the regular version. Just the tire is 23 lbs while the Blizzak weighs 18 lbs. I'll be shopping for replacement summer tires. I won't be buying another set of stock tires. They are crap with a BB rating for performance and temperature. Feel on the road matches that poor rating. Since everyone has been talking about fuel prices lately: My wife has been driving the Bolt for her 50 mile commute since I've been travelling. To date we have spent $28.67 on electricity. It is pretty crazy that we bought here a car to replace the TDI on April 4th and she didn't drive it until yesterday.