You bet.
So, to recap the whole thing. On August 08th, 2015 I had my stock NDT 9.00R20s dismounted and Goodyear G177s (11.00R20s) mounted in their place, reusing the stock wheels. I maintained duals in the rear despite the fact that the tires are rated for enough to be run as singles even on the rear axles.
I had clearance issues with the rear tires rubbing the trunnion cap and bolts. This was solved by adding a 1/4" spacer plate in the rear (3/8" or even 1/2" thick spacer plate probably would have been a little better but it depends on the length of your studs), but also important was changing out the trunnion cap hex head bolts being rubbed against, to bolts with rounded heads and allen wrench centers.
(Please remember that at this time I had the larger tires with the stock 0.187 ratio speedometer adapter so the quoted miles per hour is technically not accurate)
I only drove one trip (~60 miles) with un-modified front caster angle. At "speed" on the interstate (a good road), about 50 MPH, I did not have too much problem steering, but I grew uncomfortable with the touchy steering and the amount of concentration required to keep the truck centered in my lane as it still wanted to wander easily. When I exited the interstate to a lower quality 2-lane side road, I had to reduce my speed to ~40mph (the posted speed limit was still higher) otherwise I would have easily ended up off the road. In all honesty, I probably should have driven still slower. This required most of my concentration and effort in maintaining control of the truck. At speeds lower than ~25-30mph I really didn't notice the issue.
I then proceeded to remove my front leaf spring perches and determined which perch I had via the 2nd picture in peashooter's post here (I used the measured thicknesses as my guide):
http://www.steelsoldiers.com/showth...-G-177-tires&p=1497451&viewfull=1#post1497451
I believe I had the 2nd from the top perch, or a 4 degree perch. As shown in the first picture in the above peashooter post, I removed ~5/32" from the front perch surface. Not mentioned previously was removing 5/32" from only the front of the perch didn't let it sit perfectly flat on top of the axle. If you notice in the above linked peashooter post, it appears both sides were milled some. I just said "close enough" and bolted the u-bolts around it. I still have the stock leaf spring locator pin on the driver's side of the axle, but the passenger side had retaining blocks welded to the top of the axle housing on either side of the leaf spring perch, and an immovable remnant of the original pin still in the axle housing. I plan to keep the reused air-assist u-bolts (they were new this year, put on and taken off once), but I have new u-bolts for the driver's side as currently they are, presumably, the original ones from 1972.
The drive:
On my way to Boyce Equipment for them to weld the blocks around the passenger leaf spring perch was my first time driving with the modified perches. It should be noted that at this time my air-assist steering was turned
off. This was the first time I drove the truck with the air-assist turned off since it was installed earlier this year. I immediately noticed how quickly the tires returned to center. I did not fight the truck to keep it in lane and the ride was improved on the new tires.
With the leaf spring perch secure I turned the air-assist back on. Most of the automatic return to center is now
gone. I actually noticed this when I first put on the air-assist when still running NDTs. I strongly believe this is an artifact or trade off of the air-assist system and not of the caster or tire change.
I drove the truck to work yesterday and down an extremely bumpy road at 40-45 MPH. I did
not fight the truck. Sure, I bounced around but my tires were
not trying to follow grooves or even trying to turn. I bounced and let the truck ride rough but I maintained control of it.
The G177s are easier to steer than the stock NDTs, of course, further improved at low speeds by air-assist and should be easier on the assist since the tires are easier to turn! On concrete in my smoother concrete garage, I can turn the tires from lock to lock while stationary. Put a piece of cardboard under 1 tire and I can do this 1 handed.
Reminder, none of my experience has yet to be off pavement.
Verdict:
Only one thing could please me more about these Goodyear G177 tires, that they did not pick up rocks in the tread so easily. I am actually surprised at how much I like the tires as I REALLY liked how the Michelin XL or XLZ tread pattern looked an planned to go for those tires for about 2 years.
Caster adjustment was definitely needed and every person doing a similar upgrade as I should absolutely plan on it as a required task (or investigation at minimum). I would council great care in removing your leaf spring perches and when removing material. If it is daunting, perhaps go the non-permanent change shim route and add a shim. I believe earlier in this thread it was recommended a 1/4" to 1/16" shim (1/4" toward the rear, 1/16" toward the front), but the reader should verify that.
