Rpm I thought I could trust my ear, but wasn't certain. I've been able to cruise at 55-60 mph without sounding like I'm ready to explode. I was going to ask you all about this because everyone seems like they can't keep up with traffic. But with the above equation, my original gears and 29" diameter wheels at 60 mph I'm reving 2857rpm. Thanks Nate for driving home the need for those LT21585R16 "tall" tires and you Russ for the math. No need for new rear end for me. But I do need to get to a speedo shop so I know what speed I'm travlin' without having to call my chase car.
Skinny TALL Tires ...Are the key to getting decent highway speeds out of any old stocker . I don't recommend the use of Bias-Ply tires , they're unsafe crap , careful selection of the right LT radial will retain that period correct look old truck guys want so badly .
speedo shop Larry I went out and boughta GPS witha speed indication built in justa wee bit easier than getting your speedo and the drive gear set up ...but that is just me THakns for the explaination of tiresize and speed also guys when the snow melts and i can get the garage open Ill have to measure my tires and do the math BIll
O.K. But ; I know I'm just an old Farm/Used Car Lot/Junkyard Mechanic but I never waste any time doing the math , you're going to need those tall 30" ~ 32" tires no matter how you cut it so just go buy two and mount 'em up , give it a whirl and you'll see ~ Or , you can Hot Rod it (change engine etc.) , that's another way to make it go fast but 99 % of the folks who do this , either never finish it and scrap the previously good old truck or worse , they don't really like how it drives and loose interest and buy another Hot Rod......
Tires Yes, some tire stores in Major Cities carry them for the gardener trade as they're useful and durable no matter the brand . Most can order them up (Dayton , Goodyear , General Etc.) but will instead insist they're not available and try to sell you some other size that's " exactly the same ! " ~ B.S. it's never the same . take the time to go in person and look in the catalog if they don't have them way in the back room . most salesmen have no idea these sizes even exist .
The only LT 205 or 215/85 x 15 tires I could find were for trailers. Trailor tires are not good for car/truck use. I looked at 205/75r x15 tires. Their diameter was just over 27 inches. How does that fit into the calculations?
Ebay BF Goodrich and Michelin as well as others are available on eBay which tells me they are made, some even 10 ply rated. However, I wouldn't recommend buying them there as the shipping is a killer...
Here is what I used instead of the LT truck tires which were quite a bit more expensive. Tires: I got 225-75-R16. Firestone Destination LE. 4 tires mounted rotated, balanced for life installed for $410 They were buy 3 get one free! Gives me an overall height of 29.28”. Look good enough for me for this truck. I really like it. Here is the thread that shows what I did for mine. https://talk.classicparts.com/showthread.php?t=11532
