Question: increase tire diameter to fill wheel gap?

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Mad Hungarian

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#21
Everything you say is correct @garsh. Scrub radius applies primarily to the front wheels and is a particular problem for FWD. I know that a creative alignment shop can correct the scrub radius with camber adjustment. I am interested to hear what @Mad Hungarian has to say about this.

There are different types of wheel spacers. Some bolt to the hub and the lug bolts thread into the spacer which allows the reuse of existing bolts or have the bolts in place on the spacers. The Prius group has had the best luck with Adaptec spacers for both safety and utility.
Before we go too far down the rabbit hole, a few quick pointers for those of you who don't nerd-out on scrub radius, offset or other matters of wheel geekitude ...

Scrub radius:
Is basically what defines where the center of the tire's contact patch sits in relation to the steering's pivot point.
There's a nice, brief Wiki explanation here.
Note that changing wheel or tire width will NOT change scrub radius, but changing tire O.D. (in the limited amount discussed here) will. Not drastically, but it does.

Offset:
Is a little easier to grasp, it's the wheel spec that determines how far in or out the wheel's mounting surface is positioned relative to the center of its width. Usually found stamped on the backside of the wheel, preceded by the letters ET or IS (not always that easy, but if you can't find it and want to know yours is for any given car just ask me).
Increase it and you push the wheel further under the body. Decrease it, or add a spacer to do the same thing, and it moves the wheel outward. There are a million good articles/vids on this if you care to Google.

Spacers:
Perforated steel or aluminum discs that are inserted between the hub mounting surface and the wheel to effectively lower the offset while keeping the same wheel. Minor changes - in my book that's 3mm to 10mm - can be done as long as the following criteria are met:
- High quality construction, preferably forged aluminum
- Allows wheel to remain correctly centered, either by the original hub poking through to mate with the wheel, or on thicker spacers where the car's hub is covered the spacer should have its own protruding hub ring.
- MOST IMPORTANT: There must still be sufficient thread engagement for the lugs, Rule of thumb is one times the diameter of the fastener, so for a 12mm stud, 12mm of threads should be engaged. On a 12x1.5mm nut or bolt that would be 8 turns. If it's a bolt vehicle you can easily change to longer bolts if needed. On a stud and nut vehicle this is a much more involved process.
- Notes for this mod as it applies to Teslas as we know them today: So far we've only seen studs and lug nuts from the big T and I fully expect the 3 will be the same. They can actually be spotted in the reveal vid from a year ago. If they're anything like the ones on the S and the X the studs will be long but only threaded about 60% of their length.
x-hub-jpg.1666


So there's precious few extra threads to work with if we add a spacer. I wouldn't go more than 3mm thick without changing the studs. To make matters worse, the hub is not even 4mm long. It's the shortest I've ever seen on any production vehicle. So this means a hub-centric spacer with its own protruding hub surface is a must, and it would need to be at least 6mm thick in order to safely cover the original hub. So if they stick to this strategy on the 3 you will almost certainly be looking at swapping out the studs to make it work. Or getting lower offset aftermarket wheels (just sayin' :)).

Unfortunately I've never seen a comprehensive guide that lists what the scrub specifications are for a given vehicle, so you are left to try and find the design drawings for your particular car or go out and try to measure it yourself. You can then figure out if the offset changes you are planning will keep you in your car's "sweet spot" or not.
As someone who's played with aftermarket wheels for a living for the last 30 years I'm finding that most modern cars are not nearly as affected by minor to medium changes in offset compared to cars from the 80's and 90's. However this isn't to say that it isn't worth considering. Each model reacts a little differently, some drivers are more sensitive to the resulting changes than others, and a lot has to do with WHERE you drive. Here in the province of Quebec we are blessed (cursed actually) with some of the worst roads in the nation so we get to test firsthand what effect changing sizes and offsets does when presented with severely rutted and potholed surfaces. Most cars with a multi-link suspension like the S don't get too worked up by adding a little extra width and lowering the offset up to 10mm. So I'm going to go out on a limb and say the similar setup on the 3 should be OK with the same mild mods.

Increasing tire OD: Although it can be done, I'm just not a huge fan of this, little payout for the potential grief. As has been pointed out, if done within reason in the same increments at all four corners - say 2% - it should be fine. However I'd be extremely leery of making any staggered size changes that result in more than a 1% OD difference front-to-rear. Best case scenario is that this will anger the TC/ESC/ABS computer and result in a lot of false ECU intervention and red dash lights, worst case on AWD ICE cars is blown-up center differentials (seen more than a few of those). The wonderful thing about EV's is that even with AWD the front and rear axles live completely separate lives, so with a few keystrokes the ECU could easily be programmed to enjoy the new sizes and not set off any alarm bells. However as we know this would need Tesla's blessing and there's no guarantee they will want to support anything other than the OE approved sizes. That's until the aftermarket finally starts cracking The Code for these cars, then it'll become an arms race between Tesla and the hackers. That ought to be entertaining.
 

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JBsC6

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#22
Just wait for vendors to offer proper wheels for the model 3...in the sizes you want..

I like the 20s of the launch vehicles shown last April.

235/35/20
275/30/20

I believe we're the tires according to Melinda?..

I think that would be a cool mod for the tesla model 3...

Probably will cost less for the aftermarket too
 

JBsC6

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#24
Melinda I saw the pricing from that company and of course it's ridiculous...there are always more appropriately priced wheels available.

As you must find with your solstice gXP here in New Jersey potholes tend to eat up our wheels..

Even using the wheel straightening companies around here I've found every two years or so when I buy new tires for my current ride...I tend to buy new wheels as well.

Sometimes the wheel repair shops can't get the wheels right and it ends up being easier and less of a hassle to just buy new rims...

Usually costs me a grand or two for a new set of quality rims but not over the top crazy like the vendor you mentioned.

Stunning wheels to be sure but parking in NY city with its potholes etc , not to mention crime usually leads me to more moderately priced wheels...

I'm sure the aftermarket will respond accordingly...

There will be many who want 20inch rims like the release vehicles and want a more moderately priced examples...

If not...I'll start it myself..as I'm sure there will be a market.

Thank you Melinda...and I hope your keeping your solstice gXP for top down motoring days...

What color is your convertible?
 

Mad Hungarian

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#25
T Sportline has been doing this for S/X for a while now, but don't think you will be getting a bargain.
https://tsportline.com/shop-tesla-aftermarket-accessories-products/ts115-forged-tesla-21-inch-wheel/
Actually I beg to differ, a well-made Tesla replica can be found at a reasonable price (apologies for the shameless self-plug here):
Replika R187
They've been very well received so far.
And you can be sure that we are currently taking suggestions as to what everyone is going to want for their 3 ;)
 

garsh

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#26
And you can be sure that we are currently taking suggestions as to what everyone is going to want for their 3 ;)
Ok. I want a set of 19" wheels that are staggered like the alpha cars so that the rear wheels are as wide as will fit.
And I'd like it for about half the price of those R187's. :D
 

Mad Hungarian

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#27
Ok. I want a set of 19" wheels that are staggered like the alpha cars so that the rear wheels are as wide as will fit.
And I'd like it for about half the price of those R187's. :D
LOL! Pricing aside, that might not be as crazy as it sounds. I was thinking we'd do the alpha design in 18" square (same size all-around), 19" square and 20" staggered. But if enough folks wanted the 19" staggered we'd just need to add that rear size. We'll have to see how demand plays out...
 

ModFather

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#28
Replika R187

And you can be sure that we are currently taking suggestions as to what everyone is going to want for their 3 ;)
Nice looking rim at a reasonable price. Couple of comments: they sure seem to be heavy, I would like a different color, and directional rims look goofy going the wrong direction on one side of the car in my opinion.

Regarding your post in the large wheel thread, there is a lot to digest there but I will respond. Remember what your mother said. "chew before you swallow!"
 

Mad Hungarian

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#29
Nice looking rim at a reasonable price. Couple of comments: they sure seem to be heavy, I would like a different color, and directional rims look goofy going the wrong direction on one side of the car in my opinion.

Regarding your post in the large wheel thread, there is a lot to digest there but I will respond. Remember what your mother said. "chew before you swallow!"
Yes, because the S and the X are so heavy we had to really beef the R187 to handle their gross axle loads. Not to mention we went with regular cast construction as it was primarily targeted as a winter wheel for our market and folks are generally more concerned with spending money on the best tires for that season over the wheels. However I'd like to see if we can't make our Model 3 rep in a flow-formed process, that takes a lot of weight out of the barrel, maintains strength and doesn't add a huge amount of cost. Will depend on volume projections.
 

garsh

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#30
But if enough folks wanted the 19" staggered we'd just need to add that rear size.
I don't know how many people have tastes that match mine. I'm not a big fan of the low-profile look, but I *am* a big fan of a nice, wide tire.
This doesn't look good to me:

This does:
 

Mad Hungarian

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#31
I don't know how many people have tastes that match mine. I'm not a big fan of the low-profile look, but I *am* a big fan of a nice, wide tire.
This doesn't look good to me:

This does:
You're not alone, those of us born into the early days of muscle and exotic cars can really appreciate such proportions. One of my all time fave OE tires was the 335/35R15 on the back of the Countach...


These days I'm happy with a reasonably wide 45 series for most mid-size sedans and coupes, with maybe a wider 40 series rear where it makes sense. So likely that I'm going to be doing like you and run a stagger 19" on my 3. Lighter, faster and more comfortable than the 20's.
 
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ModFather

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#32
You're not alone, those of us born into the early days of muscle and exotic cars can really appreciate a such proportions. One of my all time fave OE tires was the 335/35R15 on the back of the Countach....
I love those white rims on that Countach! I LOVE white rims on a white car! In 1977 I had a white Porsche with white rims (red and black interior), yum,yum. Those were the days before the Stormtrooper mime. Bet you can't guess what I'm going to do this time around. ;)

I agree with @garsh , I don't like rubber band tires. Give me some meat on my tires for longevity, lower cost, and serious look. Yep, I want staggered too, but I will probably go with the 18's maybe even 17's aftermarket.

What is the bolt pattern on the MS/X? Can we assume (guess) that the 3 will have the same pattern?

Gosh, I'm getting really excited! Christmas is almost here!
 

Mad Hungarian

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#33
I love those white rims on that Countach! I LOVE white rims on a white car! In 1977 I had a white Porsche with white rims (red and black interior), yum,yum. Those were the days before the Stormtrooper mime. Bet you can't guess what I'm going to do this time around. ;)

I agree with @garsh , I don't like rubber band tires. Give me some meat on my tires for longevity, lower cost, and serious look. Yep, I want staggered too, but I will probably go with the 18's maybe even 17's aftermarket.

What is the bolt pattern on the MS/X? Can we assume (guess) that the 3 will have the same pattern?

Gosh, I'm getting really excited! Christmas is almost here!
S/X are 5x120, and my best guess from squinting at hundreds of 3 pics and the reveal vid is that it will very likely be the same. OEMs usually choose the pattern based on the vehicle's projected max gross weight, and since the estimates out there put the 3 well within 90% of the lightest S I would find it odd if they chose to go to a smaller pattern. The other thing is if they keep 5x120 they can probably share some basic hub components. Everybody LOVES to standardize stuff these days. We shall see...
 

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#34
@Mad Hungarian there is a lot of information in your posts above. Two things for me. I would love to have a spare set of no frills wheels to mount winter tires on.

The other is a question. I have 20 inch wheels on my i3 and the ride is a little more firm than I like. So would that mean I should consider the 18" wheels for the model 3 rather than the 19s? I hear the same for the model X, their wheels are 2 inches different.
 

Mad Hungarian

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#35
@Mad Hungarian there is a lot of information in your posts above. Two things for me. I would love to have a spare set of no frills wheels to mount winter tires on.

The other is a question. I have 20 inch wheels on my i3 and the ride is a little more firm than I like. So would that mean I should consider the 18" wheels for the model 3 rather than the 19s? I hear the same for the model X, their wheels are 2 inches different.
If ride comfort is a priority for you I'd highly recommend sticking with the 18" size for the 3. The 235/45-18 that I expect will be offered should offer a good comprimise between ride and handling, especially if the suspension is as well sorted as it is on its big brother. It looks to be a very similar if not nearly identical setup so I have high hopes it will be.
 

Jean Théoret

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#36
If ride comfort is a priority for you I'd highly recommend sticking with the 18" size for the 3. The 235/45-18 that I expect will be offered should offer a good comprimise between ride and handling, especially if the suspension is as well sorted as it is on its big brother. It looks to be a very similar if not nearly identical setup so I have high hopes it will be.
Is there a big difference in comfort between 18 and 19'' wheels? We can feel the diference? I'm not experience with the matter.:eek:
 

Mad Hungarian

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#38
Is there a big difference in comfort between 18 and 19'' wheels? We can feel the diference? I'm not experience with the matter.:eek:
There are a lot of variables to answer that with 100% certainty in every case. And every driver has their own idea of what acceptable ride comfort is. But as we're pretty sure that the 18" will be a 235/45R18 and the 19" will be a 235/40R19, if we assume the same tire model is used then yes, you will be able to feel that the 19" ride is firmer, most noticeably over smaller, sharper bumps. However it should be noted that the multi-link type suspension that the 3 will have is generally very good at handling larger diameter / lower profile tire sizes, my A4 with the same type of suspension rode just fine on 235/40's. So if you love the look or prefer sharper handling, I don't personally think the 19" is going to be a problem even on our horrible Quebec roads. Damage from impact will be slightly more of a risk, but no matter what you ride on around here sooner or later one of our meteor impact craters will get you :eek:.
But if you really want the smoothest ride, stick with 18".
 

KennethK

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#39
So, as a recap, have we determined that this wheel is the 19" and the aero is the 18" (with the hard V shaped fins as opposed to these swooping V wheels in the picture)?
5_xadwddoh-jpg.1751