even lighter?


A while back I mentioned that I would be considering lighter wheels and tyres. After sailing through the recent (and first for me with this car) MOT, with just an advisory about worn tyres, I decided now might be time to make this change. So here are the results:

IMG_20150424_083123 IMG_20150424_083131

The styling might not be to everyone’s taste. I have selected MAK XLR 16″ wheels which come in at approximately 6.5kg’s each and Dunlop Sport Maxx RT tyres which are summer specification but seem to be a good combination of lightweight and low rolling resistance.

I have also added aluminium wheel nuts, as much for style than weight saving but that being said they are very light. Use caution when tightening these onto steel studs as the steel will strip the thread from the aluminium. I tightened to 108 Nm as per the Leaf handbook.

The old wheels and tyres weighed in at around 19kg’s each, the new ones at 16kgs. This means 12 kg saved of unsprung rotating mass which should be equivalent to around 48kg’s saved from within the vehicle. Add this to the lightweight lithium battery, replacing the original lead acid unit and I have saved 52kg’s.

Whilst this is not big beer it is the equivalent of ejecting a slender adult passenger from the car. I have reset my energy efficiency counter on the dash so I can now measure how the average kwh/mile figure changes. That being said it only reads out in units of 0.1 kwh/mile so the effect of this change might be lost since units of 0.1,0.2,0.3 are not that accurate.

Also there was in Bristol a recent front page article in the Bristol Post about the scandal of £1m being spent on electric vehicle chargers for the Green Capital 2015, that Bristol now holds. I could not find it on their website but it would seem this is something to cheer about rather than complain about!

Also it is worth mentioning that 6.5kg wheels are pretty light for cast aluminium, but forged aluminium can be lighter still, around 5kg for a 16 inch wheel. The lightest wheels are carbon fibre at around 2kg per wheel but easily several thousand pounds each!