Wheel swap - suspension adjustment required?

[Fas-T]

I recently changes the LT stock highway tires 255R17 with all terrain 265R18 including new rims (Al both). Running over bumps on the HWY, I have the feeling, the wheels are bouncing. Do you think the suspension or shocks need pre pressure adjustments?

[CamGTP]

There are zero adjustments for that.

 

Your only option is to swap struts and shocks for a better product than the OEM parts. Tires play a role in this as well. Certain tires ride worse than others and the stock 255/70/17's have lots of sidewall, so they run pretty smooth on the open road.

[Gangly]

16 hours ago, Fas-T said:

I recently changes the LT stock highway tires 255R17 with all terrain 265R18 including new rims (Al both). Running over bumps on the HWY, I have the feeling, the wheels are bouncing. Do you think the suspension or shocks need pre pressure adjustments?

There are no "pre pressure adjustments" on the factory suspension.  If the vehicle isn't handling the way you think it should then your options are limited to taking it back to the dealership to check for any issues, or upgrading your suspension components. 

 

Since you didn't give the complete dimensions on the new or old tires, its possible that you have a smaller sidewall now and your feeling the difference.