Rubber To The Road: Why Tyres Are Crucial To A Solar Car

It’s all about resistance this week, and by that we mean tyres, if you can’t make the car more streamlined or any lighter, you get the best tyres you can so that you minimise rolling resistance; that is the force against the motion of our wheels when they’re moving. You probably know by now that you lose some energy whenever friction is involved, and this is all about minimising that.

Tyre image via Shutterstock

The solar car gets 16-inch rims, with the drive coming from two CSIRO-Marand Solar car electric motors in the rear (that’s right, rear wheel drive so we can drift in the snow…) and you could just shove a set of bike tyres on there if you liked, but tyres have a great effect over 3000km and we’ve heard from our little birds that in the last race, they’re what separated the peloton. So instead of doing that, we’re going with bloody expensive, tyres, at €500.

The Michelin Solar Car Radial tyre is 5x less in rolling resistance than a standard energy saving car tyre. That means, the energy it takes to move the car will be 5x less than your little hatchback, though it also means you wear through the tyres incredibly quickly. Over a 7 day race, in the middle of the desert and starting numerous times, you better bet we’d go for the best, Particularly since last year the teams that placed 1st, 2nd and 3rd all used these, accompanied by their million-dollar budgets.


Usually these tyres are incredibly difficult to get your hands on; initially in fact, you could only get these tyres through direct sponsorship from Michelin International in France. We have to thank the UNSW team though, who are on-selling us some they acquired, particularly since usually the limited allocation is reserved for the very best known and best run teams.

Once these are attached to our brand new, single disc monocoque carbon fibre rims, also specifically made for this tyre in japan and you’ve got a world beater. Each rim weights about 1.2kg and can support 200kg per wheel. That’s a good thing when the car only weighs 250kg with the driver.

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In other news, and completing our United Nations of solar car, we’ve sent our SunPower solar cells to Germany to be professionally encapsulated and etched. What this means is you take the individual cells, and turn them into the modules (panels) you want. Every cell has to be placed and each panel is custom made so that we have the best shape for our car. Then, specifically for higher efficiency, the surface that goes on these cells, which both protects and enhances them, is etched so that more light can bounce or focus through than on a typical clear and reflective surface.

It’s been a good week and soon we’ll have all our parts coming in from around the world, so that we can take on the world.


25 engineering and industrial design students from UWS are working together to build a car powered entirely by the sun, ready for a race across the spine of Australia. In October next year the team will race the car from Darwin to Adelaide as the underdog, pitted against better funded rivals. Gizmodo has been supporting the University Of Western Sydney's push to build a Solar Challenge car for this year's Sun-powered race between Darwin and Adelaide. After much hard work, careful planning and many scrunched up pieces of paper over late nights, we're proud to help introduce you to this year's medal contender: The Solace — proudly supported by Gizmodo.

Support the UWS Solar Challenge Team! If you have marketing/sponsor dollars (hello car makers, telcos and electronics multinationals) or engineering support to donate, please contact Greg at UWS Solar Car.

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