4/6 Drop and 20x8.5 Wheels Tire Size
 

Looking for advice on what size tires to run in the front (86 C10). I have been looking at other truck specs and it seems everybody runs around a 40 series tire, but wondering what you guys thought of a 45 series tire (cheaper). Do you guys think I would rub the inner fenders?

Re: 4/6 Drop and 20x8.5 Wheels Tire Size
 

There are more variables to your question that make it hard for anyone to repsond with any real accuracy. A 45 series would be fine in say a 245 but maybe not with a 255 or 265...Also depends on the b.s. on the wheel and size of wheel diameter as far as actual measurements go. In summary, some 45's will work...some may not. You need to figure out what OD will work and how much room you have for width. Then look at the actual specs of different tires and see what fits. You can have two 255/45 series tires made by two different brands and they will measure different. Im running a 45 series tire on my truck with a 4/6 drop but its a 245/45/18 with a 4.5 b.s. A 245/45 for a 20 may measure diff than mine and rub... Once you offer all of the variables to the equation, I know there are a bunch of guys on here that will probably chime right in. Maybe take a look at the actual specs of some 245/45/18's and find similar specs in a 20inch tire?? Hope this helps.

Re: 4/6 Drop and 20x8.5 Wheels Tire Size
 

I just put a 5/6 kit on mine over the weekend with new 20x8.5 & 20x10 Boss wheels. I'm running 245/45 upfront and 275/45 in the rear. My wheels have a 5.25 backspace upfront with plenty of room, but a 4.75 backspace may need a 40 series tire. My tires are sitting dead level with the fenders, no gap was what I wanted. I hope that helps.

Re: 4/6 Drop and 20x8.5 Wheels Tire Size
 

I measured the backspace on the front wheel and it came out to 4.5

Little more background on the wheels:

They are Intro Pentia's with a 5x5 bolt pattern, but the backspace was originally for a Grand Cherokee. So I went online to motorsporttech.com and had them make 1.5" wheel adapters.

I could not pass up the deal on the wheels.

Nice truck btw!