Can an 8" Width Wheel be Used for the Model 3 LR

[SageBrush]

I own the Model 3 LR and am shopping for 18" diameter wheels and winter tyres. Discount Tyre shows me both 8" width and 8.5" width wheels as compatible with the car but the user manual states 8.5"

Do I have a choice, and what are the trade-offs ? My interest is in cost, since the narrower wheel is about $50 cheaper per wheel.

 

[run-the-joules]

Narrower wheels = narrower tires = less contact patch area = less traction in most conditions

Also less rolling resistance, I suppose.

 

[Brando]

I own the Model 3 LR and am shopping for 18" diameter wheels and winter tyres. Discount Tyre shows me both 8" width and 8.5" width wheels as compatible with the car but the user manual states 8.5"

Do I have a choice, and what are the trade-offs ? My interest is in cost, since the narrower wheel is about $50 cheaper per wheel.

I own the Model 3 LR and am shopping for 18" diameter wheels and winter tyres. Discount Tyre shows me both 8" width and 8.5" width wheels as compatible with the car but the user manual states 8.5"

Do I have a choice, and what are the trade-offs ? My interest is in cost, since the narrower wheel is about $50 cheaper per wheel.

Tires are very important. IF you drive - what min. speed on Colorado FreeWays? 55? - matters a little less. Higher speed the more important the tire. I'd stick to Tesla recommended tires.

winter tires (snow, ice, wet)
summer tires for max grip and best braking distance - even though few of us ever emergency brake.

In my 900 I always bought the Michelin OEM spec tires. Except this last time, mostly bike & walk. about 10 years ago and for the first time I experienced hydroplaning, on a curve, sun shine water running across the highway, less than 1 year old. So now I'm very careful in wet conditions. When you figure the cost/mile it just isn't worth any savings in my experience.

Only you know your driving conditions. Risk factors, just your life or wife or kids etc. Do/can you avoid bad weather conditions. you get the idea. In Colorado, I'd get both winter and summer tires/wheels so you could easily change. Narrow tires also work a little better in wet - more weight / patch area.

good luck with your choices.

 

[SageBrush]

Narrower wheels = narrower tires = less contact patch area = less traction in most conditions

Are you saying that an 8" width wheel cannot accommodate a 235/45 tyre ?

 

[timk225]

The 3 should have an 8" wheel, not 8.5, for a 235 width tire. The sidewalls are angled slightly the wrong way, looking at them from the rim to the tire tread.

 

[SageBrush]

The 3 should have an 8" wheel, not 8.5, for a 235 width tire. The sidewalls are angled slightly the wrong way, looking at them from the rim to the tire tread.

hmmm.

235 mm is 9.25 inches

 

[ℬête Noire]

Are you saying that an 8" width wheel cannot accommodate a 235/45 tyre ?

The tire's manufacturer will give a range of rim width that they feel is acceptable for the tire. An example here: https://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Blizzak+LM001&partnum=345VR8LM001XL&vehicleSearch=true&fromCompare1=yes&autoMake=Tesla&autoYear=2018&autoModel=Model 3&autoModClar=Rear-Wheel Drive

Scroll down and select the "Spec" tab. Then look under the "RIM WIDTH RANGE" column. You'll see that Bridgestone feels this tire in size 235/45R8 is safe on 18"x7.5" through 18"x9" rims. Thus both 8" and 8.5" rims aren't even at the edge of manufacture's specs. This is very typical of 235 tires.

You do also need to watch what the rim's offset spec is (how far the surface that sits on the hub is inside/outside of the center of the wheel rim) and how that interacts with the non-standard rim width. This potentially results in the edge of the tire sitting closer in towards the suspension/inside wall of the wheel well or coming out closer to the edge of the fender, thus a risk of rubbing.

That's unlikely to be an issue here since you aren't going to wider tires than OEM but this is where a pro tire installer, as opposed to some rando on the Internet like me, can help you make safe choices by doing the math.

 

[SageBrush]

That's unlikely to be an issue here since you aren't going to wider tires than OEM but this is where a pro tire installer, as opposed to some rando on the Internet like me, can help you make safe choices by doing the math.

VERY informative -- thanks!

I'll take your advice and walk into a store tomorrow although my prior experience is that the Rep relies on a computer program. Perhaps we can take a stab at this question here: if the proposed wheel is 0.5 inches narrower and the offset is 40 mm (the same as OEM), what does this say about the position of the tyre and wheel relative to OEM ?

Do you happen to know how much inside clearance there is with the 18" OEM setup ?

 

[timk225]

Back when I had my 1971 Plymouth Valiant and similar old cars, it was common to put 205 and 215 width tires on 5.5 inch wide rims, because that was what was available as OEM steel wheels. Of course, those were 14 inch wheels, so the 70 and 75 series sidewalls had more room to flex.

 

[Oyster Bait]

VERY informative -- thanks!

I'll take your advice and walk into a store tomorrow although my prior experience is that the Rep relies on a computer program. Perhaps we can take a stab at this question here: if the proposed wheel is 0.5 inches narrower and the offset is 40 mm (the same as OEM), what does this say about the position of the tyre and wheel relative to OEM ?

Do you happen to know how much inside clearance there is with the 18" OEM setup ?

The math seems to work out that the inside clearance shouldn't change since the offset is the same. The .5" narrower wheel should mean that the outer rim is less susceptible to curb rash because the tire should take the initial rash abuse.

 

[ℬête Noire]

VERY informative -- thanks!

I'll take your advice and walk into a store tomorrow although my prior experience is that the Rep relies on a computer program. Perhaps we can take a stab at this question here: if the proposed wheel is 0.5 inches narrower and the offset is 40 mm (the same as OEM), what does this say about the position of the tyre and wheel relative to OEM ?

As I understand it:
Stock offset is +40mm. 0.5" * 25.4mm/" = 12.7mm narrower / 2 = 6.35mm so you'd need roughly +34mm offset to be centered the same. There are, likely not coincidentally, a huge number of 35mm offset 18"x8" rims matching Tesla's bolt pattern.

Do you happen to know how much inside clearance there is with the 18" OEM setup ?

It appears that on the front inside the tightest point, even with full steering turn both ways, is one finger thickness in height, about 1.5 finger thickness horizontal inside. ((EDIT: This in on an AWD, not sure if that part is different on the RWD? )) Yeah, I've been checking up on tires but living on the Gulf Coast I'm headed the other way with wider summer tires that end up somewhat shorter, so I've got a lot more room to work with. It looks like I'm going to 245/40R18 that are something like 8mm shorter (but a lot squarer shoulders, Tread Width is 9" vs 7.8" on stock tires).

So about 6-7mm maybe? It's the piece of suspension, in line with the axel, that curves over the inside corner of the tire. The Model 3 has a lot of wheel gap stock so the fenders shouldn't be much of an issue unless you go crazy.

Because you're in CO though, are you going to need to worry about clearance for chains? Just on the rear or front and rear? Also watch that 235/45R18 is only a ballpark. The tread width also matters (Tesla's stock wheels have fairly rounded shoulders, a squarer tire with wider tread width will be tighter on that suspension) and actual height can vary a few mm because of tread depth. Further, all those measurements are from a fixed rim size. For 235 tires all the size spec numbers are for 8" rims (see the column "MEAS. RIM WIDTH" in the link above). When mounted on a 8.5" rim they'll have slightly different dimensions as they flex to adapt to that rim.

 

[ℬête Noire]

Ok, my finger is more brutish than I thought. It's more like 12mm clearance on top, and something over that on the sides.

 

[monkeyracer]

I've got 18x9.0 +40 wheels with 265/40ZR18 Tires on my Dual Motor 3 right now.
I'm getting 18x8.0 +45 wheels with 235/45R18 Winter Tires installed this week.
The wide tires clear with no problems at all.
The winter set up is the same rim as the summer set (Konig Rennform Flow Forged) but, the 8" width is only offered in +35 or +45. The +45 was available now, vs the +35 available in a couple of weeks.
When comparing the +45 offset 8" wide wheel with the OEM +40 offset 8.5" Aero 18" wheel, the inside lip will be in the same place (same backspace), and the center of the tire will be 5mm inboard (less than 1/4"). If they made these in a +40, I would have gotten them without hesitation, and would have preferred the +35 as a second choice, but didn't want to wait a couple of weeks to get these installed. I will probably try 5mm spacers to get the center of the tires exactly where the OEMs were designed to be. (Which is the same as my 265 set up: match the offset to match the location of the center of the tire.)

As far as the tire, in my opinion, the OEM 235 is too narrow for the 8.5" wheel (as mentioned above), and a 235 is better suited for the 8" width. There is also more tire to help guard against curb rash since the wheel is tucked in a little further.

In short, an 8" will work great for the OEM 235 width tire. Just make sure that you are getting a wheel that is rated for a higher weight vehicle. Some of the cheaper wheels are not certified to withstand the extra weight and could be a dangerous option.

 

[SageBrush]

Just make sure that you are getting a wheel that is rated for a higher weight vehicle. Some of the cheaper wheels are not certified to withstand the extra weight and could be a dangerous option.

I bought an inexpensive wheel so this sounds like a good question. In the spec sheet all I could find was a tire load rating of 1800.

Does that mean up to 7200 pounds car weight ?

 

[Snow Drift]

Narrower wheels = narrower tires = less contact patch area = less traction in most conditions

Also less rolling resistance, I suppose.

Not in the winter. You want narrow wheels/tires to cut through deep snow. In the summer you want wide.

 

[Snow Drift]

I own the Model 3 LR and am shopping for 18" diameter wheels and winter tyres. Discount Tyre shows me both 8" width and 8.5" width wheels as compatible with the car but the user manual states 8.5"

Do I have a choice, and what are the trade-offs ? My interest is in cost, since the narrower wheel is about $50 cheaper per wheel.

The issue is will the 8” depth, coupled with the design of the spokes, clear your brake calipers? Depends.

Example, I have 19x8.5 +50 on my STI and use 18x8.5 +44 winter rims...but a lot of spoke designs in that size won’t fit bc it’s a big 6-pot brake kit. So, you need to use trial and error (or let a shop do the research before buying).

Don’t just trust TR or a discount website. They said wheels would fit without actually testing. I needed an actual shop who sold wheels for my car to test fit.

 

[run-the-joules]

Not in the winter. You want narrow wheels/tires to cut through deep snow. In the summer you want wide.

Hence "most conditions"

 

[SageBrush]

I ordered the cheaper wheel and expect installation in about a week. Discounttire added a $55 'kit' to my order and a $5 concentric ring. I presume the ring is to push the wheel outwards; no idea what is in the 'kit.'

Anybody know ?

 

[miimura]

I ordered the cheaper wheel and expect installation in about a week. Discounttire added a $55 'kit' to my order and a $5 concentric ring. I presume the ring is to push the wheel outwards; no idea what is in the 'kit.'

Anybody know ?

TPMS?

 

[SageBrush]

TPMS?

Unrelated.

I have the TPMS sensors, bought as a side purchase and programmed by one of our own.