Tag: tyres

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Model Y Tyres: be one step ahead to keep the costs down.

I’m hoping the instances I’ve seen in the past week with regards to uneven tyre wear on 2023 WA based Model Ys is just pure coincidence rather than being widespread across the Australian fleet, in saying that it’s best to be prepared by spotting any uneven wear early and booking the vehicle in for a check and alignment.

How can you spot an issue early?

If you look at the tyre surface from the front or the rear it can be very deceptive, tyre wear may look very even across the tread and wear on the outer edge is fairly easy to spot. On the other hand wear on the far inside edge is almost hidden until it’s too late, that’s why getting a tyre rotation or inspection done 10,000kms after delivery is well worth the effort. Taking the wheel/tyre off and rolling it slowly while carefully checking the surface will show up any early signs of uneven wear.

Check the inner edges when the tyres are off.

Why bother?

If a looming safety issue doesn’t sway you to be vigilant maybe some basic arithmetic  will, a 19inch tyre on a Model Y that has even tyre wear throughout its life should survive for at least 50,000kms, if you don’t correct uneven wear early the tyre is likely unroadworthy at 30,000kms, that’s approximately $800 worth of tyre tread wasted. For those vigilantly counting every cheap kWh of electricity you charge your Tesla with you may be wasting more on tyres per km than you’re spending on electricity per km.  If you have a Model Y with higher priced Pirellis it’s closer to $1100 wasted.

Fitting new tyres

Hopefully you get even tread wear and a high km lifespan out of original set of tyres but eventually they’ll need replacing. Unless you can find a compelling reason to change brands I’d recommend sticking with a similar Hankook 19, Michelin 20 or Pirelli 21 that Tesla factory fitted, often keeping it simple is the best method.
Without doubt most Model Ys in WA will be fitted with 19inch Hankook Ventus EvoS1 (255/45/19) I recently got a quote for these at $499 each, that’s reasonable but I highly suggest you make enough phone calls to get not only a competitive price but a tyre shop that will respect both you and your car.
Hankook have also recently introduced a similar tyre specifically for Electric Vehicles called the Ion AS, in the 255/45/19 size I received a quote for $539 each.

I’m sure you’re asking this question; “Is an EV specific tyre marketing BS?” The answer will be revealed soon as one of our members is currently putting the Hankook Ion tyres through a thorough long distance test across the top end of Australia.

In summary:
Keep a constant check on your tyres, it only takes two minutes while the car is on charge.
Correct the reason for uneven wear ASAP.
Phone around for competitive tyre prices in the weeks before you need new tyres not on the day you find your car unroadworthy.

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A Tale of Two Motors

Test Number 2

After seeing the results from test number 1, How much do 19 inch tyres and wheels improve the performance of a Tesla Model Y, it was decided to do a second 272 km test (along the same route) between the same Model Y Performance with 19 inch Gemini wheels and tyres and a Standard Model Y with exactly the same wheel and tyre set-up.

The clear difference between these two vehicles is their drive units. The Performance Y has dual motors with a maximum of 393kW power, whereas the Standard Y has a single motor producing a maximum 194kW. The Performance Y is 88kg heavier than its standard range stable-mate due to a combination of different-sized battery packs (and chemistry difference) and the extra weight of its additional motor. The operating parameters of the two cars were identical with tyre pressures set to 42 psi cold, air conditioners set to 22°C and the same number of occupants in each car. You can read in the initial test all the steps taken to obtain an untainted result.

Model Y
Performance
19″ Gemini		Model Y
Standard
19″ Gemini
Leg 1
31km		206Wh/km198Wh/km
Leg 2
105km		164Wh/km165Wh/km
Leg 3
105km		153Wh/km156Wh/km
Leg 4
31km		 98Wh/km105Wh/km
Total
272km		157Wh/km158Wh/km

Test start 9.05 am, completion 12.42 pm. Weather, clear skies temp 13 – 20°C. Moderate wind from the same direction for the whole test which reflects in the result for Legs 2 & 3.

Please note the Performance Y once again recorded a total trip of 271 km over a 272 km journey, the other two test cars both recorded 272 km.

Although the Performance Y is heavier than the Standard Y and also has a second drive unit which slightly adds to mechanical friction losses, these disadvantages are likely compensated for by it being about 14 mm closer to the ground. Since reduced ground clearance enhances efficiency at higher speeds, a test in stop/start city conditions would likely slightly favor the Standard Model Y.

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How much do 19 inch Gemini Wheels and Tyres improve the Energy Efficiency of the Model Y Performance?

The only way to correctly test energy efficiency is by having two similar cars driven on the same roads at the same time over a reasonable long distance.

This test was conducted using two almost identical 2023 White Model Y Performance vehicles built in the Shanghai factory within days of each other. Both had covered over 1,600kms in the first week of ownership. Both had aircons set to 22°C. Both had cold tyre pressures of 42psi. Both had two occupants. It is crucial to note that neither car used the Williams Supercharger to navigate to and thus battery preconditioning was NOT used to avoid contaminating the results. During the test, the cars were driven no closer than 60 metres at highway speeds with the biggest gap being approximately 400 metres. Each car drove the front position for half the journey.

Cars were driven at the speed limit (max 110km/h) as much as possible with overtaking of slower traffic only conducted on designated overtaking lanes. Luckily traffic flow was generally good during the whole test.

To be clear, the test was conducted mostly on the Albany highway, a coarse road surface that’s consumes plenty of energy and is often used by Tesla drivers visiting the Great Southern.

Over the total 272km test (136kms south, 136kms north), the Performance model Y with factory fitted 21 inch Überturbines averaged 178Wh/km while the Performance model Y with the 19inch Gemini rims and hub caps (acquired from a new standard range model Y) averaged 158Wh/km, an improvement of 11%. That’s not a typo, that’s eleven percent with every other aspect of the two cars being identical.

There’s two main factors that cause the difference in energy efficiency: The 21inch Überturbines have what could be described as “sticky” Pirelli tyres, great for putting down the power and torque of the dual electric motors under extremely hard driving, but energy hungry in general driving. The 21 inch wheel/tyre combo has less smooth tyre surface and more rough wheel surface on the outside of the car. The Gemini wheels have more smooth tyre surface and a fairly smooth hub cap so airflow at higher speeds is less interrupted. If you’re a City Slicker, the 21 inch Uberturbines are fine. If you plan on long distance driving away from reliable DC charging, the energy wasted may be an issue.

Model Y
Performance
21″ Überturbines		Model Y
Performance
19″ Gemini
Leg 1
31 km		212Wh/km195Wh/km
Leg 2
105 km		168Wh/km149Wh/km
Leg 3
105 km		200Wh/km175Wh/km
Leg 4
31 km		105Wh/km95Wh/km
Total
272km		178Wh/km158Wh/km
TOCWA Note: Distance per Leg is approximate
  • Leg 1: Byford to Albany Hwy T junction. Moderately uphill, average speed 64 km/h
  • Leg 2: T junction to Williams Woolshed Supercharger. Moderately downhill, average speed 97 km/h
  • Leg 3: Return Williams Woolshed to T junction. Moderately uphill, average speed 102 km/h
  • Leg 3: T junction to Byford. Moderately downhill, average speed 71 km/h

Conditions: dry 22°C to 29°C, light winds. Start time 9.30 am, finish 1.15 pm.

Überturbines (left photograph), Geminis (right photograph). Both “Since Charge” screens did not reset to zero as per normal after Supercharging???

This test was conducted by Harald Murphy and Rob Dean, two of the most experienced long distance drivers in Australia.

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Why do my tyres wear faster than another Tesla’s tyres?

First up there is a myth that EVs wear tyres faster than a similar size petrol vehicle due to the extra weight. There has not been a detailed study on this and to be clear if there was a widespread study with dozens of vehicles over many years and large distances the far smoother accelerating and braking of an EV would offset tyre wear from the extra weight. The problem is the myth has a strong foothold so many EV owners use it as an excuse for their excessive tyre wear.

Tyres have a large amount of information moulded on to the sidewall.  As well as the sizing there’s also the speed index, weight index and tyre wear rating, a number normally between 200 and 500. A higher number suggests a longer lasting tyre but there is a possibility that a small amount of grip could be sacrificed so think carefully before changing from the tyres fitted in the factory by Tesla, especially the performance models.

So even after considering the tyre wear rating you’re still getting far less distance from the same tyre/vehicle combo as another Tesla owner, why could this be?

Poorly maintained tyre pressures – Stick to the cold pressures recommended by Tesla and check them on a regular basis. Keep in mind to check during the first few hundred metres of a drive before the tyres heat up.

A high amount of driving on coarse chip seal country roads.

A high amount of driving in built up areas with stops signs, traffic lights and most of all roundabouts.

Failing to rotate the tyres.

Possible misalignment due to a family member hitting a kerb or a pothole and not owning up to it.

And lastly, your driving style. No one wants to hear this but the combination of low centre of gravity and lack of engine noise lulls EV drivers into thinking they’re driving slower than they really are, but in reality your cornering faster, accelerating faster and generally putting the tyres under more pressure than you would in most petrol cars, continually driving like this scrubs the tyres out in no time at all.