[Kaseikei]

I have an 18LT with the 20inch wheels.

Due to busting one of my stock run flats i'm in the market for new tires. I saw a good deal on P Zero's 245 45 20. Can i run these in the rear of the car?

I think i read some thread that in the front it would be an issue. But can i shop around and look for a rear 245 45 20 and front 245 40 20?

Thank you.

[arpad_m]

Originally Posted by Kaseikei

I have an 18LT with the 20inch wheels.

Due to busting one of my stock run flats i'm in the market for new tires. I saw a good deal on P Zero's 245 45 20. Can i run these in the rear of the car?

I think i read some thread that in the front it would be an issue. But can i shop around and look for a rear 245 45 20 and front 245 40 20?

Thank you.

There will definitely be a tangible difference in height/circumference and revs per mile (see below). Since the new tire you're looking at for the rear is taller, wheel rotation will be slower, so I don't think this will mess up ABS or Stabilitrak, although I don't know the actual trigger thresholds, plus your speedo and mileage will be off a bit.

https://tiresize.com/comparison/

[Kaseikei]

Thank you for the reply i will look into this.

[samr350]

That's a pretty big difference front to rear and may cause abs/tc issues.

[arpad_m]

Originally Posted by samr350

That's a pretty big difference front to rear and may cause abs/tc issues.

It'd be awesome if someone with actual knowledge of the thresholds and the algorithms chimed in, hopefully this trivial stuff isn't protected IP.

I recall earlier posts about people wanting to increase rake by using taller rear tires and not seeing issues, but this is definitely a bit dicey at 3.6%. As another data point, my tires are also a bit different from OEM, but the difference is 0.9% (or 1.1%, depending on which way one looks at it) and I have zero issues.

[samr350]

Originally Posted by arpad_m

It'd be awesome if someone with actual knowledge of the thresholds and the algorithms chimed in, hopefully this trivial stuff isn't protected IP.

I recall earlier posts about people wanting to increase rake by using taller rear tires and not seeing issues, but this is definitely a bit dicey at 3.6%. As another data point, my tires are also a bit different from OEM, but the difference is 0.9% (or 1.1%, depending on which way one looks at it) and I have zero issues.

Everything I've seen has said don't go over 2% front to rear or you'll start having issues with stuff like ice mode. It was confirmed by GM somewhere but I can't find it exactly. I do know that someone went over 2% and had ice mode and didn't when they went back under 2%. I think they were around 3%.