Just got my wheels back from having them powdercoated gloss black and when they were mounting the tires back on they noticed the rear wheels were 2 different sizes and offsets. 20x9.5 +40mm and 20x10 +35mm!! And no it is not front vs rear because the fronts are 20x9 which were correct. Installer was advised to make sure the correct tires went on the right rim and this is how they found the different wheel sizing.Now i have to bring them back to tesla and see what they say. Does anyone know of any running changes they had for the rear wheels? I have a Dec 2018 x p100dl. Took delivery in June. Hope i dont have any issues getting them to fix this and hopefully get reimbursed for having them powdercoated again. Smh part numbers 102724500c & 102722500a. Anyone know if the performance are suppose to have the 20 × 10 ?
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P100DL - 2 Different Rear Wheel Sizes !!
- Thread starter shadowinstallz
- Start date
Mine was a demo/showroom car so it was probably in an out several times. I'm thinking they changed out one of the rears when they were getting the car prepped and just used whatever they had lying around and didnt notice. My wheels were the only tesla x 20s being done at the time. So no mix up.
I realize this is an "older" thread, but I just discovered it, and I am currently interested in the rear wheel size difference.
Background (for my benefit and for readers not familiar with wheel/tire information)
Tesla wheel rim nomenclature, such as "20x10J +35mm," means:
(America's Tire) ------------------------------------------ (Les Schwab)
As we may know (or have found out the hard way), it is very important to select the correct wheel sizes--diameter, width, and offset--so the the wheels do not rub or otherwise interfere with brake, fender, and suspension components. In addition, these can dimensions affect the aesthetics (appearance) and ride of the car, and can also have major impacts to handling and safety.
Model X apparently always had "staggered" wheel sizes, (in this case) meaning that the rear wheels were designed to be slightly wider than the front wheels.
Apparently, earlier (~2016) Model X came with 20x10J +35mm rear wheels? Then at some point (~2017) they switched to 20x9.5J +40mm wheels?
Modified from Les Schwab website figure.
(Not fully to scale and not truly representative of Slipstream wheels.)
I suspect, but do not know) that this change was made to reduce the likelihood of wheels/tires rubbing on other components. Nonetheless, there are plenty of older (used) Tesla Model X and new aftermarket 10-inch wheels still in the marketplace.
The current Tesla Parts List indicates that new replacement 20-inch Model X wheels are:
March 2021 to present (for comparison)
I am no expert. From what I can tell, dealing with changes to wheel and tire sizes can be tricky, especially the further one ventures from stock specifications. In looking at used wheels and tires for sale in my area, I have already seen evidence of poor choices made (e.g., rear wheels installed at the front leading to worn grooves on the inner wheel rims.
Furthermore, with its air suspension and control settings Model X has the capacity to change vary ride height (which can affect wheel/tire positioning, possibly cause rubbing(?), and also negatively affect tire wear.) Unless you really know what you are doing, for safety's sake I recommend that folks stick with current stock specifications on wheel and tires.
The OP Issue
I cannot predict how deleterious, if at all, it is to be outfitted with 20x10 35mm and a 20x9.5 40mm rear wheels at the same time. If this had happened to me I would be examining:
Buyers looking at aftermarket and used Tesla wheels and tires: BEWARE!
In my experience, this is one of the most danger*-fraught areas for Tesla (and autos in general) consumerism. There is a TON of misinformation, both accidental and purposeful, out there. Especially on the Internet, but even at otherwise legitimate brick-and-mortar establishments. Be extremely careful when buying used and new-old-stock tires from private sellers and used tire/wheel dealers. Likewise, do your homework before investing in aftermarket and (claimed) Tesla wheels. It is a (tire and wheel) jungle out there!
______
* Meaning the chance for misinformation, and hence for resulting poor purchases, is higher than normal. Since we know that--as the contact point between the car and the road--wheels and tires are so important, this situation is troubling. It is interesting to note that something like at least 40% (last time I looked) of all TMC Classified ads are concerned with tires and wheels.
Background (for my benefit and for readers not familiar with wheel/tire information)
Tesla wheel rim nomenclature, such as "20x10J +35mm," means:
- 20-inch diameter (point on edge of bead seat to point 180° opposite on edge of bead seat)
- The "bead seats" are the protruding circular edges of the outer and inner faces of the wheel that help grab and secure the beads (inside edges) of the the tire.
- 10-inch wheel width (from outer bead seat to inner bead seat).
- 35mm wheel offset--"the distance from the [inner] mounting surface of the wheel [where the lug bolt holes are] to the wheel's outer-inner center-line, given in millimeters." (from America's Tire website)
(America's Tire) ------------------------------------------ (Les Schwab)
As we may know (or have found out the hard way), it is very important to select the correct wheel sizes--diameter, width, and offset--so the the wheels do not rub or otherwise interfere with brake, fender, and suspension components. In addition, these can dimensions affect the aesthetics (appearance) and ride of the car, and can also have major impacts to handling and safety.
Model X apparently always had "staggered" wheel sizes, (in this case) meaning that the rear wheels were designed to be slightly wider than the front wheels.
Apparently, earlier (~2016) Model X came with 20x10J +35mm rear wheels? Then at some point (~2017) they switched to 20x9.5J +40mm wheels?
Modified from Les Schwab website figure.
(Not fully to scale and not truly representative of Slipstream wheels.)
I suspect, but do not know) that this change was made to reduce the likelihood of wheels/tires rubbing on other components. Nonetheless, there are plenty of older (used) Tesla Model X and new aftermarket 10-inch wheels still in the marketplace.
The current Tesla Parts List indicates that new replacement 20-inch Model X wheels are:
March 2021 to present (for comparison)
- 20x9J ET40 - front Cyberstream (I believe ET ["einpresstiefe"=insertion depth] 40 = +40mm?)
- 20x10J ET35 - rear Cyberstream
- 20x9.0 ET35 - front Helix
- 20x9.5 ET40 - rear Helix
- 20x9.0 ET35 - front Slipstream (three color variations)
- 20x9.5 ET40 - rear Slipstream
I am no expert. From what I can tell, dealing with changes to wheel and tire sizes can be tricky, especially the further one ventures from stock specifications. In looking at used wheels and tires for sale in my area, I have already seen evidence of poor choices made (e.g., rear wheels installed at the front leading to worn grooves on the inner wheel rims.
Furthermore, with its air suspension and control settings Model X has the capacity to change vary ride height (which can affect wheel/tire positioning, possibly cause rubbing(?), and also negatively affect tire wear.) Unless you really know what you are doing, for safety's sake I recommend that folks stick with current stock specifications on wheel and tires.
The OP Issue
I cannot predict how deleterious, if at all, it is to be outfitted with 20x10 35mm and a 20x9.5 40mm rear wheels at the same time. If this had happened to me I would be examining:
- Original rear tire wear.
- Any evidence of rubbing on either side of the undercarriage.
- Online information.
- How you made out with Tesla Service?
- Whether you were able to replace one of the rear wheels?
- What the final outcome was?
*****
Buyers looking at aftermarket and used Tesla wheels and tires: BEWARE!
In my experience, this is one of the most danger*-fraught areas for Tesla (and autos in general) consumerism. There is a TON of misinformation, both accidental and purposeful, out there. Especially on the Internet, but even at otherwise legitimate brick-and-mortar establishments. Be extremely careful when buying used and new-old-stock tires from private sellers and used tire/wheel dealers. Likewise, do your homework before investing in aftermarket and (claimed) Tesla wheels. It is a (tire and wheel) jungle out there!
______
* Meaning the chance for misinformation, and hence for resulting poor purchases, is higher than normal. Since we know that--as the contact point between the car and the road--wheels and tires are so important, this situation is troubling. It is interesting to note that something like at least 40% (last time I looked) of all TMC Classified ads are concerned with tires and wheels.
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I meant to directly reply to your OP in my posting, above (but forgot to do so)...
What has prompted my interest in rear wheel sizes are my plans to install Tesla Sonic Carbon 20" Slipstream wheels on my white early-2021 Model X. I'll probably powdercoat a spare set of Slipstream wheel rims I already have, but I've also been looking for used factory Sonic Carbon wheels. And I started noticing (e.g., on eek!-Bay) used rear wheels with both 20x9.5 and 20x10 widths.
Really curious to know how your situation turned out--whether you changed out one of your rear wheels, and if so which size you settled on for the rear?
Yes, this is an interesting issue (to me). Key questions I have include:
- Is having different sized rear wheels (even those that are pretty close, but still different) a significant problem?
I assume that for normal (non-racing) highway driving we should always use the same sized wheels (and tires) on the left and the right side of each 'axle.'
- Given a choice between 20x10J 35mm (+35mm) and 20x9.5J (40mm), which size is now considered to be best for the rear of a Classic (2015-2021) Model X?
I would like to know why Tesla changed the specification? Did Tesla determine that the 20x9.5 (+40mm) size was an improvement for all Legacy Model X? Or should early Model X continue to use 20x10J (35mm)? Was there ever a safety or technical bulletin about Model X rear wheel size?
- What if anything happens if you run the two sizes? (Maybe nothing? Or maybe handling or wear suffers?)
- Since the overall rear-wheel rim width decreased (by ½" = 12.7 mm)--I assume 1/4" on each side of the center-line?--but offset increased (by 5 mm = ~0.197" = ~1/5"), how did positions of inner wheel surface parts (e.g., bead seats and mounting surfaces) actually change in relation to the car?
Perhaps the inner bead seat did not change its location much in relation to the car. Instead, it may be the outer bead seat that changed, moving inward slightly and giving more clearance of the fender? (Do I have that right?)
- If 20x9.5J (+40mm) was found to be "better," why did Tesla return to 20x10J (+35mm) for refreshed Model X Cyberstream wheels?
Did something about the Model X axles change?
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Crude graphical analysis (in Excel) of the effects of Model X rear-wheel size changes. For this analysis I am assuming no change in tire size. Instead, two wheel dimensions did change: (a) wheel width (from 10" to 9.5") and (b) offset (from 35 to 40mm).
Adding one-half the wheel width to the offset distance gives the distance from the inner bead seat (inner edge of the rim) to the inner mounting surface:
Subtract the results from the wheel widths gives the distance from the inner mounting surface to the outer bead seat:
If I am visualizing this correctly (in three dimensions, not my forte), it may mean that a 9.5-inch wheel should have a similar amount of clearance on the inner side (e.g., to next to brake and suspension equipment) with a small amount of additional space on the outer side (next to fenders).
I don't know why Tesla made the size change to rear Slipstream wheels, but it may have been to alleviate potential rubbing under certain conditions--e.g., when towing, with a heavy internal cargo load, with the suspension lowered or raised, when navigating bumpy roads, in hot temperatures (when tires can over-inflate), et cetera. (That's just a guess. Perhaps it had nothing to do with potential rubbing,)
Cross-Sectional Diagrams of Hypothetical Model X Rear Wheels
20x10J (+35mm) (on left) versus 20x9.5J (+40mm) (on right) Wheels
20x10J (+35mm) (on left) versus 20x9.5J (+40mm) (on right) Wheels
Adding one-half the wheel width to the offset distance gives the distance from the inner bead seat (inner edge of the rim) to the inner mounting surface:
- 5" + 35mm (= ~1.38") = ~6.38" for the 10-inch-wide rear wheel, and
- 4.75" + 40mm (= ~1.58") = ~6.3 for the 9.5-inch-wide rear wheel.
Subtract the results from the wheel widths gives the distance from the inner mounting surface to the outer bead seat:
- 3.62" for 10-inch wheel,
- 3.175" for the 9.5-inch wheel.
If I am visualizing this correctly (in three dimensions, not my forte), it may mean that a 9.5-inch wheel should have a similar amount of clearance on the inner side (e.g., to next to brake and suspension equipment) with a small amount of additional space on the outer side (next to fenders).
I don't know why Tesla made the size change to rear Slipstream wheels, but it may have been to alleviate potential rubbing under certain conditions--e.g., when towing, with a heavy internal cargo load, with the suspension lowered or raised, when navigating bumpy roads, in hot temperatures (when tires can over-inflate), et cetera. (That's just a guess. Perhaps it had nothing to do with potential rubbing,)
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Shuttlecraft X
Member
After reading this thread I just ran out and checked my tires...the dealer had just put new ones on when I bought my used Model X and it turns out I have 275/45R20s on all four wheels so I don't know what the heck that means. It's supposed to be 265s in the front and 275s in the rear. How can I tell if the wheels are 9.0 or 9.5 while they are mounted? What are the pitfalls of running 275s in the front?
that s a lotta questions idk how to answer...
the rear needs better load bearing for towing purposes and perhaps wider tires for better traction to tow?
20x10 switcheroo to 9.5 bc they realized ain t nobody is gonna do heavy duty towing w ev bc when u supercharge you take up the whole lot?
size is preference? some likes it long some likes it wide? idk
but i do know that symmetry in all things mechanical is a priority...
dealer is an idiot...
besides rubbing issues it s just not spec...
take it back and tell them do it right...
Agreed. (I wonder if the dealer will object to making any change/correction?) I assume that this was not at a nearby Tesla Service Center (Rocklin [original area SC], Sacramento [relatively new], Vallejo [relatively new]), correct? (I am in Yolo County also!)
I have read that it is OK to use a Model X front wheel/tire as an emergency spare in the rear. But that it is not OK to use rear wheel-sets in the front. It was recently brought home to me why this is so:
The other day I got the chance to examine four used Model X Slipstream wheels for sale on Craig's List. Unfortunately, I found that all four were rear wheel-sets (275/45R20s). The wheels that had been used in the front of a Model X had major grooves worn into the inner edge of the metal rims. Not good for the rims or for the suspension/brake equipment that was making contact. That is apparently what happens when you use rear Model X wheels up front. ('Important safety tip, Egon.')
For the benefit of readers, the normal 20-inch tire/wheel specifications of the ("Classic," "Legacy") Model X (in this part of the USA) was often:
- front (Continental) tires: 265/45R20 108V (CrossContact LX Sport T0)
front (Slipstream) wheels - 20 x 9.0J +35MM
- rear (Continental) tires: 275/45R20 110V (CrossContact LX Sport T0)
rear (Slipstream) wheels - 20 x 9.5J +40MM
Apparently the brand of 20" tires might have varied--e.g., for winter tires, and/or in certain regions (Michelin, Good Year?)--and of course was different (Pirelli) for the 22-inch performance tires.
As I mentioned in Post #5, BEWARE of all tire/wheel sellers, especially used-tire sellers (whether businesses or private individuals) on-line (where tires are frequently repaired/plugged). Do your homework and be prepared to indicate exactly what you need/want. Otherwise, you may get what they want to get rid of that day. (Like dealing with emergency plumbers and other contractors.)
Until I learn otherwise, I will continue to assume that it is best to get spec-correct wheels/tires. Model X uses staggered wheels/tires--wider in the rear--for a reason, I believe.
Lastly, I understand that many people want to replace the stock Continental tires with other brands (for various legitimate reasons). As long as whell and tire sizes stay within appropriate (factory) limits, that should be totally OK, afaik.
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Shuttlecraft X
Member
You are correct, this was not a SC but a dealer in the Roseville Automall. I risked buying a used Tesla at a dealership that knows nothing about Teslas and I've certainly learned my lesson now. I sort of knew what I was getting into owning a Tesla as my previous brand new Model 3 was in the SC a few times before everything got worked out. This morning the USS in the passenger side FWD fell off inside the door and now both passenger side doors will open right into anything in the way. I've got a call into EV's Republic to see what all of this is going to cost me. Also, it was raining the day I bought the MX and I didn't see that the upper exterior seals on both FWDs are FUBAR. *sigh*
I still don't know what the situation with the tires truly is...do I have two rear wheels on the front of the car or did they squeeze 275 tires on the front wheels...Even though they are new Goodyear tires I absolutley hate them anyway as they are deafening on the highway. How do I tell if I have 9.0 or 9.5 wheels?
Sorry.
Right. What are the (front) wheel sizes? (Rear, too?)
That is relatively easy. Written on one inside (back of) spoke of each wheel. So take the car to any tire/wheel place (that knows the proper way to raise a Model X—with jack pads) and have them check all four wheel sizes. Check for any rubbing damage, also.
You could do it at home, but difficult.
- Raise air suspension to its highest.
- In an open area somewhere (empty parking lot?) carefully position each wheel, one by one, so that the spoke with the wheel size (see photo in Post 16) is visible (oriented towards the ground). Before you do that, One of us could send you a photo of the back of a wheel so you can see what info is on each spoke, and in what spoke order (e.g., wheel size, Part Number, "Made in China," Tesla emblem, etc.), to help in finding the right spoke. (Turns out I had such a photo already.)
- Use cell phone camera or mirror on a stick or whatever to visually inspect the inside of the spoke in question.
- Or alternatively, remove the wheels, one by one, if you have a proper jack, jack stand, and jack pads. (Be careful.)
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Here is a photo of the back of one of my spare rear Slipstream wheels.
Assuming that the order of information written on the Tesla Slipstream wheel spokes is consistent among wheels of different (a) ages, (b) countries of origin, (c) position (front vs. rear), et cetera, this may help you find the key spoke (the one with wheel size).
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Shuttlecraft X
Member
Thank you so much!!! That is very helpful! I'm really enjoying the TMC community because there are so many people like you who are willing to take time out of their day to help others. 
Thank you so much!!! That is very helpful! I'm really enjoying the TMC community because there are so many people like you who are willing to take time out of their day to help others.
You are welcome. I don't know about others, but I am really liking the back side of the Slipstream wheels (even more than the street-side). Looks cool. Too bad we can't mount the rear wheels (powder-coated and with hub cover) with that side facing the street. (Ha, ha.)
The 20x9.5 ET40 rear wheel will work up front with 5-6mm of spacer, if necessary, on legacy X. I've done it, it's fine as a spare even with the 275 on it, plenty of turns on the lug nut too. If that's all you've got you're not stranded. You can't just bolt it on or it hits the upright, must use a spacer. I imagine the same will be true for the 20x10 ET35s, because the slightly lower numerical offset is "offset" by the additional half inch (about 6mm in each direction inboard and outboard) of width, but I've not tried it.
There's lots of room to go wider up front (see many many wheel/tire threads with very wide aftermarket setups), so long as you can get the offset right, and even more room in back.
As for two different-offset, different width wheels in back, so long as the tire is the same, I don't think it's a big deal. It should be corrected, but considering you're authorized to drive around on a donut spare for miles at 55mph in various vehicles, it's not exactly a showstopper to have a tire that's the right size in back on a slightly different wheel. We aren't launching a moon rocket here. Up front there is room for the 275 tire, but it'll hit stuff on a rear wheel unless you space it out, and the "preferred" or "factory" square setup on this car is a 265 all around (for winter 19's) not 275's. But there's room, if you move things around a bit, obviously or the car woulnd't have moved. On a factory *front* wheel, I bet the 275 doesn't hit anything either, it's pinched more and spaced out by a little less than half an inch (narrower by half an inch, plus 5mm) relative to the rears
Luckily the rear tires will wear out fast and you'll already have two spare 275's after you get the proper front tire on there! lol
BTW the T0 Continental tires are no longer available in the US other than old stock, it's a revised T1 code with different foam and possibly other changes
Congratulations on discovering wheel offset and fitment nerdery, it is fun.
There's lots of room to go wider up front (see many many wheel/tire threads with very wide aftermarket setups), so long as you can get the offset right, and even more room in back.
As for two different-offset, different width wheels in back, so long as the tire is the same, I don't think it's a big deal. It should be corrected, but considering you're authorized to drive around on a donut spare for miles at 55mph in various vehicles, it's not exactly a showstopper to have a tire that's the right size in back on a slightly different wheel. We aren't launching a moon rocket here. Up front there is room for the 275 tire, but it'll hit stuff on a rear wheel unless you space it out, and the "preferred" or "factory" square setup on this car is a 265 all around (for winter 19's) not 275's. But there's room, if you move things around a bit, obviously or the car woulnd't have moved. On a factory *front* wheel, I bet the 275 doesn't hit anything either, it's pinched more and spaced out by a little less than half an inch (narrower by half an inch, plus 5mm) relative to the rears
Luckily the rear tires will wear out fast and you'll already have two spare 275's after you get the proper front tire on there! lol
BTW the T0 Continental tires are no longer available in the US other than old stock, it's a revised T1 code with different foam and possibly other changes
Congratulations on discovering wheel offset and fitment nerdery, it is fun.
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Yes, and that is why I am pretty sure "T0" signifies 'Tesla Zero' and not 'Tesla Original,' as some people claim.
I got some of those T1 tires (with improved? foam) from Tesla a few months ago. It is like when Tesla part numbers change from _________-A to _________-B, and then _________-C. (Or when firmware number designations change to indicate modifications.) The number is indicating an update, but not a complete overhaul, to an original product.
I've seen photos of Continental tires for Mercedes and Porsche where they do the same thing.
