nicd01

So I successfully converted the cars brakes, in so doing I got some or bearings and changed the rear tires to 285/35/18 up front 245/40/18, I am having serious traction control issue, at 60 mph it comes on , I have to lift off to reset it, any ideas?

RIHI

I'm not 100% sure but I think, the corresponding rear tire to a 245/40-18 front tires are 275/35-18.

Mrmandmman

Your aspect ratios are a bit different.

245/40R18 = 25.7x9.7R18
285/35R18 = 25.9x11.2R18

275/35R18 = 25.6x10.8R18

Your tires may be rotating at different speeds, which at high speeds could be enough to trigger the traction control.

nicd01

We checked with a live scan and rotating speed was nearly identical, within 1kmh. But perhaps you are right
This is the difference 245/275
Diameter 653.2mm 649.7mm
Circumference 2052.1mm 2041.1mm
Poke 65mm 92.7mm
Inset 151mm 148.7mm
Speedo error 0% 0.54%
Reading at 30mph 30mph 30.16mph
Reading at 60mph 60mph 60.32mp

This is 245/285
Diameter 653.2mm 656.7mm
Circumference 2052.1mm 2063.1mm
Poke 65mm 92.7mm
Inset 151mm 148.7mm
Speedo error 0% -0.53%
Reading at 30mph 30mph 29.84mph
Reading at 60mph 60mph 59.68mph

MiniNL

It's the difference in tire size. It sucks given that you have the tires now and it's expensive to swap out again. If you're gonna go staggered, best is 245/45/18 & 275/40/18 as they are exactly the same. I'm not sure if I'd want to put the strain on the x-drive, but to each their own.