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18-inch winter wheels?

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Zagor

New Member
Nov 7, 2013
1
0
Sweden
Hi guys. I'm sort of windows shopping for a Model S and it has been very interesting to read the adventures of owners experiencing the car in harsh winter climate. Since I live far north, this matters to me.

It is a little unfortunate that the Model S only comes with 19 or 21-inch wheels. The range of winter tires in those dimensions is rather limited and very expensive. But I wonder if perhaps 18-inch wheels could fit. Has anyone physically tried fitting 18-inch wheels to their car?

The limiting factor to downsizing wheels is typically the brakes. The disc and caliper needs to fit inside the rim. The rear (largest) disc of the Model S measures 365x28 mm. I compared with the BMW M5 (E60) and it turns out it has much larger brake discs: 374x46 mm. Yet the M5 can be fitted with 18-inch wheels. BMW even sells 18-inch OEM wheels for the M5.

So unless the calipers of the Model S are significantly bulkier than those of the M5, 18-inch wheels might actually fit. That would open up a much broader selection of tires in dimensions 245/50/R18 and 225/55/R18.
 
The limiting factor to downsizing wheels is typically the brakes. The disc and caliper needs to fit inside the rim. The rear (largest) disc of the Model S measures 365x28 mm. I compared with the BMW M5 (E60) and it turns out it has much larger brake discs: 374x46 mm. Yet the M5 can be fitted with 18-inch wheels. BMW even sells 18-inch OEM wheels for the M5.

Anyone tried 18 inch wheels?
 
If you go with 18" wheels - you want 225/55-18 - its the EXACT same tire diameter as the 19" 245/45 thus nothing will change - except you WILL get a lot better 'dig' into the snow - with better go ahead traction - you will lose some handling - but its snow application.

The exact same diameter only narrower - its called a Minus 1 conversion. Nothing is going to rub - the tire is the same diameter - and being narrower you get more clearance.

I did it in my wife's Saab for years when we lived in Connecticut and she NEVER once got stuck. Ever.
 
OK the suspension is the problem.
Yes, at least for the front wheels on the Model S, it’s NOT the brakes that are the limiting factor for wheels that will fit, it’s the steering knuckle (I believe that’s what it’s called). This is based on my experience shopping for 3rd party 19” wheels for my summer tires

example photo below: these are 19x8.5 wheels mounted on my 70D - the manufacturer’s website said they would fit the MS but as you can see while there’s plenty of room for the brakes, there’s only a paper-thin clearance for the steering knuckle at the bottom. (No, I did not buy these wheels!). Moral of the story is you can’t simply go by the brake rotor/caliper dimensions

9C25A84B-046D-49D8-9DF6-FC18F9112CF1.jpeg
 
f-stop, what are the offset on that 19x8.5" wheel? Perhaps 18x8"et40 or so will fit?
The OEM 19” wheels are 19x8.0 et40
The pictured wheel above is 19x8.5 et35 (though again as mentioned, those particular ones have a clearance issue on the inner diameter)

The other wheels I ended up buying in the end for my summer tires were also same, 19x8.5 et40. I don’t know if 18x8 et40 would fit or not...
 
If you go with 18" wheels - you want 225/55-18 - its the EXACT same tire diameter as the 19" 245/45 thus nothing will change - except you WILL get a lot better 'dig' into the snow - with better go ahead traction - you will lose some handling - but its snow application.

The exact same diameter only narrower - its called a Minus 1 conversion. Nothing is going to rub - the tire is the same diameter - and being narrower you get more clearance.

I did it in my wife's Saab for years when we lived in Connecticut and she NEVER once got stuck. Ever.
Wait so is this true or not? did anyone get 18" wheels for S for winter driving?