Front end vibration

Hi all, new to the site. Recently I experienced front end vibration or a wobble. I felt it as I was transitioning thru an intersection where the road crowns, I was going about 40-45 at the fastest. I checked frontend components and lubed. Had the tires rebalanced. The truck is a '03 5.3 4X4 Tahoe LT with 50K. The only modification to truck is 20" wheels/tires. Size is 275 55 R20. Backspacing I don't know but width is 9.5". Pretty sure the wheel/tire combo is same as OE. Wondering if anyone has experienced this problem. Thanks in advance. Joe

New shocks might help. Also...bushings that Chevy uses are real soft and tend to wear out quickly.

check your front brakes. maybe your rotors are warped

Rotors are good, no vibration on application of brakes at all. I'd never suspect the shocks with 50k but I'll check it out. Thanks

When you get to +4 and bigger wheels (20 and up), wheel manufacturer should become a concern. Sometimes we get so caught up in getting dubs on our rides that we disregard what gives a name brand wheel its reputation for what looks good on our rides; quality! Be it from chrome/powder coat quality, to wheel symmetry and balance! The lower quality wheels (mainly the ones made in china) tend to sometimes be "out of round" or "out of balance" excessively that they often cant be balanced by a tire shop to "0" thus causing the vibration! Try changing (one tire at a time) fronts to back and see what happens then!

May want to check the hubs and then have an alignment check, too. It could be that the shocks are overwhelmed w/ the larger wheels...do you know if they're alot heavier that the stock ones?

Thanks for all your replies, 69frdkiler, I did as you suggested and found the two of the tires out of round. I just put a new set of Goodyears on it and the vibration is gone.
Thanks again