I ordered 2" wheel spacers off of e-bay that were for jeep or ford, but they ended up not fitting my truck, they were 5 lug on 4 1/2" (114.3 mm) Center Bore 2-7/8". what size would i need for a 98 f150 4x4 w/ extended cab?

 

Can't answer your question, but I hear spacers are HELL on your bearings!

 

really... i dont get how but ive heard they put strain on them too, maybe i just wont use them.

 

5x135 or 5 x 5.5

 

Your truck is 5x135mm. That is not the same as 5x5.5".