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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M3P hesitates with new rims in 1/4 mile run
- Thread starter silverflash
- Start date
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.
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:
tiresize.com
It will show you the relative speedometer differences as well.
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.
It will show you the relative speedometer differences as well.
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.
It will show you the relative speedometer differences as well.
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...
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
I know you're kidding. Batman was driving that black and yellow Panamera!
Sure, 5.7% is a lot. If the 18" aero wheels (and assuming 235/45r18 tires) are selected in the wheel configuration menu, that gets ya down to about 5% which is sadly still significant.
I'm just not sure if the computer can or does make any reliable comparisons between GPS calculated acceleration and drivetrain speed sensors at lower speeds, since the rate of acceleration is much higher. (Quickly changing data from one set of sensors and slowly changing calculated data is only useful for long term trends.) Does being in track mode make a difference? Drift mode shouldn't have an issue with weird wheel speed readings... I'm not sure if the OP was in track mode at the drag strip. I'm almost certain not while on the way home when the issue was also experienced at higher speeds.
If GPS data is used to make the comparison (and not accelerometer data), maybe I can put a little tinfoil hat over the GPS antenna?
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? But the real question is why would it bother, and if it cares that much, why doesn't it throw an error instead of just putting a power dip in?
I guess it could actually integrate speed from the accelerometers and see that the inertial speed doesn't match the wheel RPM? But the real question is why would it bother, and if it cares that much, why doesn't it throw an error instead of just putting a power dip in?
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?
I agree that it's doubtful GPS is used on the fly for instantaneous adjustments, but if the computer counts wheel revolutions over a longer period of time and compares it to the GPS data, it could assume something is amiss.
Good to know! The local venue is pretty tight so the course speeds are kept down...
Were you in track mode when it tripped?
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
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.
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.
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.
Danny
Maybe. Multiple issues:
1) Wheels are drilled for 12mm diameter studs. Tesla is 14mm. Oversizing them wouldn't be a huge deal, since the cone profile for the lugnuts would be unaltered and they would still center themselves.
2) While I can't be certain (without drilling out the lug holes), it did look like I would need a rather large spacer to clear the knuckle upright and that might not leave an adequate number of wheel stud threads for the nuts. The barrels do clear the calipers, though. ha
I don't want to drill out the wheels only to find there aren't enough threads on the lugs when a spacer is used, or that the tires I have are truly too small of a diameter. lol
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 think
I wonder if it was just a difference in track surface. First, there was good prep and lots of traction, so there was uninterrupted acceleration. Second time, there was some residual oil from a car that ran in between, or the top surfaced changed due to another car spinning their tires across it (wearing off the goo, or depositing marbles, or whatever) so there was a little bit less traction, so there was a little bit of wheelspin, so the car reduced power briefly to fix the wheelspin.
Or, if the fast runs were all in one lane, and the slow runs were all in the other lane...
Or, if the fast runs were all in one lane, and the slow runs were all in the other lane...
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