Not long after the Model YL arrived, I started staring at its wheels. Specifically, I wanted to know the Model YL caliper clearance, because nobody anywhere seemed to have measured it.
The car comes on 19-inch wheels with aero covers clipped over them. With the covers on you cannot see a thing behind the spokes, so there is no way to judge how big the brakes are.
Since I need winter tyres before the cold arrives, I would much rather drop to 18 inches. Whether 18s physically fit a Model YL, though, is a question the internet had no answer to.
So back in June I pulled a cover off and measured it myself.
Four reasons I want 18-inch wheels
The first is what winter tyres cost. Nineteen-inch winter rubber is brutally expensive, so dropping a single inch makes a real difference.
The second is ride quality. Going down an inch raises the aspect ratio, which means a thicker cushion of air. The Model YL rides firm, so softening it for the winter months would be welcome.
Third, tyres themselves are cheaper in the smaller size, which helps every time I replace them.
Fourth, efficiency. Lighter wheels with lower rolling resistance ought to count for something. My efficiency figures at the two-month mark are in two months, 10,000 km in the Model YL.
Getting the aero cover off is the first obstacle
The covers are seriously stiff.
There is a plastic removal tool in the car’s toolkit, so I used that. Under load it flexes in a way that feels moments away from snapping. I spent the whole job wishing I had a spare.
Afterwards I found a proper hub cap removal tool on AliExpress for the Model 3, Model Y, and Model YL. The tip is a hook that catches the lip of the cover so you can pull it straight off.
I plan to have one on hand before I snap the plastic one in the boot.
I should also be honest about the damage: taking a cover off will almost certainly mark the wheel. The tool has to be forced into the seam where the cover lip meets the wheel face, so there is no obvious way around it.
Flip one over and you see clips right around the circumference, which explains the stiffness. It feels like overkill, though I suppose that beats one flying off at motorway speed.
This is the face underneath. Quite a different look from the covered version.
Measuring the Model YL caliper clearance with wood
Finally, a view of the brakes. The caliper is more modest than I had pictured.
I measured the front, with the car on the ground rather than jacked up. Reaching through the spokes, I aimed for the tightest point where the caliper comes closest to the inside face of the wheel.
The method was crude: cut several pieces of wood to different thicknesses, then try each one in the gap. There is no room to get calipers in there, so a pass-fail fit is far more reliable.
13.5 mm goes in, 14 mm does not
This was the last piece that slid in cleanly.
Pulled out, measured, it came to 13.5 mm. The next piece up, at 14 mm, would not go in.
So on the factory 19-inch wheel, front Model YL caliper clearance is 13.5 mm (0.53 in). More room than I expected, which had me briefly optimistic.
The rear has more room than the front
Later that evening I looked at the rear as well.
The rear caliper is visibly smaller than the front. It is the pale block sitting further back.
Looking in from the rim, the space is obvious. It was clearly past 13.5 mm without needing the gauge.
Which means the front is the only measurement that matters. Clear the front, the rear follows.
An 18-inch wheel eats 12.7 mm of the radius
Here is the problem.
The arithmetic leaves 0.8 mm
Going from 19 inches to 18 inches takes an inch off the diameter, so 25.4 mm.
Clearance is a radial measurement, so only half of that counts against me. Half of 25.4 mm is 12.7 mm.
Take 12.7 mm off 13.5 mm, you have 0.8 mm left.
Which is nothing. Everything moves under heat, under load, so 0.8 mm really means “currently not touching”. I wrote the idea off on the spot.
Except the same sums were wrong on my G05
The reason I cannot quite believe those numbers is that I ran this exact exercise on a BMW G05 X5, where the arithmetic was flatly wrong.
The G05 came on factory 20-inch wheels, with a tightest point at the top of the front caliper of about 10 mm. Dropping an inch costs 12.7 mm, so on paper I was 2.7 mm short. Guaranteed interference.
I bought a set of 19s at auction anyway, fitted them, they went straight on. Better still, the gap to the inside of the wheel afterwards was somewhere around 3 to 4 mm.
Calculated as 2.7 mm short, measured as 3 to 4 mm spare. Six or seven millimetres of the difference came purely from the shape of the wheel.
Rim profiles vary enormously between brands in how the barrel is drawn in, how the spokes are relieved. Simple subtraction does not decide it. The dealer told me it would not fit, the tyre shop told me it would not fit, on the G05 it fitted. A seasonal wheel swap on that same G05 is written up in changing the summer tyres on the BMW X5 G05.
Where that leaves the winter wheel plan
Front Model YL caliper clearance on the factory 19-inch wheel is 13.5 mm. Wood at 13.5 mm goes in, 14 mm does not.
An 18-inch wheel costs 12.7 mm of that, leaving 0.8 mm on paper. As a number, it fails.
But I have personally watched this calculation miss by six or seven millimetres, so I suspect the right wheel might still clear. It comes down to finding a barrel with deep enough relief.
Realistically this gets settled by trial fitting, which on the G05 meant gambling on a set of wheels. If any Model YL owner has already run 18s, I would love to hear about it before I spend the money.
There is still time before winter, so I will keep hunting for an 18-inch wheel with a generous inner profile. Details on the Model Y range are on Tesla’s own site. If I find a promising candidate, that will be the next article.
This article is also available in Japanese.
