BMW i8 Tires and Efficiency

Wheels, Tires, Brakes

I have seen 21 inch wheels and 245 /275 width on a i8.

There seems to be clearance for a slightly wider tire, but BMW cautions against it.

The i8 was built with that size of tire for performance – since it’s an AWD vehicle, it doesn’t have the traction issues of a typical rear wheel drive sports car, so doesn’t have the same need for wider tires. Plus, the wider/larger the tire, the more it weighs, and can cause a slight decrease in performance (although would it even be noticeable?).

From Peter Norby’s blog:

Here’s the test results, pics below as back up documentation:

City driving: Hwy 101 at 65 degrees, average speeds were 30mph to 50mph. Speeds shown are due to lots of stop signs and streetlights. Eco pro mode fan on.

@21 miles electric range, 4.1 miles per kWh, 25.2 mph. (gas engine starts)

Highway driving, Hwy 5 to San Clemente and back, cruise control set to 70mph, 65 degrees, traffic very light, eco pro mode, fan on. You will see the speed increase as the first four miles are city roads to Hwy 5.

@22 miles electric range, 4.2 miles per kWh, 57.5 mph. (gas engine starts)
@30 miles, 98.8mpg, 57.5 mph (first dip below 100mpg)
@40 miles, 71.7mpg, 59.8 mph
@50 miles, 61.2mpg, 61.6 mph

If you drive it like a beast in sport mode, no EV range and 25 mpg. (I know this from experience and it will put more miles back on your EV range)


I’ll start off every day with a full charge, and my personal driving habits are:

55% of my trips are below 20 miles RT and will be done on all electric.
15% of my trips are below 30 miles RT and will be at 100 mpg.
10% of my trips are below 40 miles RT and will be at 70mpg.
10% of my trips are below 50 miles RT and will be at 60mpg.
10% of my trips are longer and may be as low as 28mpg.

(minus 10% of the above because I like to flick it over to sport mode every now and then



Incredible efficiency and incredible performance in this beautiful work of art and engineering.

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