Different Size Tires

BGTV8

Rear tyre diameter is ~30 mm smaller with your new rear tyres and my guess is the stability control is confused, and thinks the rear wheels are breaking into wheelspin with your steering inputs and it is intervening (maybe applying one brake to avoid a slide.

OEM rear is 245/45R18 and diameter is ~678mm, your new 245/40R18 diameter is ~654mm.

You need to do one of 2 things, and that is fit the proper rear tyre size, OR get smaller front tyres fitted to match the rears (235/40R18 will go close). Be best all round to fit 245/45R18.

The answer to your question is therefore "YES".

Zis4me

are you saying I should get 245/45/18 for every tire. and not stagger it?

BGTV8

No, simply suggesting that going back to the OEM tyre size for the rear is the most logical solution.

People need to realise that vehicles fitted with ABS and Stability Control rely upon the front and rear wheels rotating at the same speed and this can be affected by fitting tyres ith different diameters than the manufactiruer intended, because that affects one of the most basci stability control parameters.

If you are changing tyre sizes, then make sure that you respect the relationship between overall diamter of fronts and rears.

Your tyre shop should have been aware of this.

Masa

Ding ding ding! Winner.

The problem is now your rear tires are 1 inch diameter less than the fronts because of the 40 series sidewall. You need 45 series sidewall with a 245 width.

Right your your front 225/50/18 have an overall diameter of 26.8 inches and the rear 245/40/18 have an overall diameter for 25.7 inches. This is a 4% variance which will throw your abs/vdc out of sync causing instability issues.

You want to stay within 1% variance when running staggered set ups.

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Jeep Cherokee Trailhawk

roplusbee

This!

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