sandohno7
Member
For M3P square setup, Apex recommends 265/40/18 tires to replace stock 235/35/20. The tire diameters for those 2 sizes are very close.
Tesla Model 3 Wheel & Tire Fitment Guide
Tesla Model 3 Wheel & Tire Fitment Guide
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Thanks @MasterC17...this confirmed what happened on my old wheel setup. Did 255/40 on a 19x9.5 et 35 and initial driving it was ok but at higher speeds the car was jerking and the TC light came on. Wasn't sure what it was but I downsized after that and then no issues. 26.8" looks like the max but I've seen a lot of previous posts prior to the install saying it fits and no issues.Ok so the overall diameter of that tire is only 25". The smallest OEM option, the 18" MXM4 is 26.3". That's a pretty massive difference of 5%. The ABS/DSC/TC/AutoPilot/Odometer/etc were not designed to compensate for such a large difference.
I would only run tires with an overall diameter between 26" and 26.8" (1.1% max difference from stock options).
I stand corrected. Running 255/35/20 and no issues.Thanks @MasterC17...this confirmed what happened on my old wheel setup. Did 255/40 on a 19x9.5 et 35 and initial driving it was ok but at higher speeds the car was jerking and the TC light came on. Wasn't sure what it was but I downsized after that and then no issues. 26.8" looks like the max but I've seen a lot of previous posts prior to the install saying it fits and no issues.
I guess Tesla AWD system is finicky.
Hey Danny, I didn't expect to find you in this thread after talking about it yesterday!One of the best things to do before buying tires of different sizes from factory is to use a tire size calculator to compare with OEM size.
General rule of thumb is you don't want to run bigger or smaller than 2% from OEM.
I use this site:
Tire Size Comparison
Tire size comparison the easy way. Use our tire size comparison calculator to compare diameter, width, sidewall, circumference and revolutions per mile.tiresize.com
It will show you the relative speedometer differences as well.
Hey Erik!Hey Danny, I didn't expect to find you in this thread after talking about it yesterday!
Has anyone experienced this TCS issue at speeds below 70mph and/or in track mode?
I have a 2021 M3P and some 255/35r18 autocross tires (from another car) that I could have mounted, but won't bother if there are issues at autocross speeds...
I know you're kidding. Batman was driving that black and yellow Panamera!Hey Erik!
One thing you need to know about me is... I AM BATMAN. haha jk
255/35/18 is -5.7% smaller in overall diameter than the factory Uberturbines setup.
That should be far enough outside of TC parameters to make it bug out on you.
Danny
As far as the speed displayed on the speedometer, it's either going to average the wheel speed sensors or transaxle sensors. In a 2wd car, I've had a speedometer indicated 70mph while barely movingCan anyone explain how the car knows how fast it's going with different sized tires?
Having different diameter tires on the front/rear would be a clear issue. But if all the tires are the same diameter, all the car knows is RPM of the wheel. How would it sense that they were off?
I really doubt it uses GPS. Someone should try this in a tunnel
I guess it could actually integrate speed from the accelerometers and see that the inertial speed doesn't match the wheel RPM? Why would it bother?
Good to know! The local venue is pretty tight so the course speeds are kept down...Never tripped below 65mph for me
I've had my Tesla doing 150 MPH with all the wheels off the ground. It works like a normal car.As far as the speed displayed on the speedometer, it's either going to average the wheel speed sensors or transaxle sensors. In a 2wd car, I've had a speedometer indicated 70mph while barely moving
Yes it tripped in track mode as well.Good to know! The local venue is pretty tight so the course speeds are kept down...
Were you in track mode when it tripped?
Details, please.I've had my Tesla doing 150 MPH with all the wheels off the ground.
That's somewhat surprising and too bad.Yes it tripped in track mode as well.
Did you run into issues on the suspension arm side?That's somewhat surprising and too bad.
It turns out the 18x9" wheels I had from another car won't fit without pretty wide spacers and I wouldn't feel comfortable going that route without longer wheel studs. So, the smaller tire experiment for this weekend is nixxed.
Maybe. Multiple issues:Did you run into issues on the suspension arm side?
Danny
IMO GPS calculated speed is not reliable enough to key things that could cause the car to grab the brakes to it. I can't imagine they're using anything but a plausibility table like you say. We'd be hearing about a lot of weird behavior I'd thinkI've had my Tesla doing 150 MPH with all the wheels off the ground. It works like a normal car.
The question is - if it can eventually work out that the tires are too small, and the GPS and speedo don't match over long times:
1) Why does it care? As long as all 4 corners are the same diameter, everything like ABS, TC, ESC, etc would work fine.
2) Why is the only result of this slow 1/4 mile times? Not other errors?
I think this is more likely tied to the fact that Tesla manages the power output of the motors very specifically based on acceleration. WOT is not always full power, and WOT on flat ground may not be full power. In this case, I can see the computer being confused about acceleration measured as wheel speed change (with an assumed diameter) vs power output, and limiting power in this case.