wheel offset, it isnt just about clearance and looks

been chasing ghosts for several years trying to get van to handle better at speed. my original issue was a very well hidden rear spring perch that the p.o. 'wrapped' with sheet metal. it looked factory original complete with precision bends/flanges and surface rust! I had replaced any and every front end part, found plenty that I swore was the issue but nothing made much difference. during the process, I installed offset rims and new tires. my true issue masked any ill effect of the deep dish rims. after towing home from the 45th nats (it had become unsafe over 35) I finally found the problem. fixing the spring brace section made it much better, but just not like it was 5 years ago. added front and rear sway bars, adjusted toe in from one extreme to the other and castor from zero to 11 degrees and everything in-between! it was still a white knuckle ride at interstate speed. local car shows and rarely a truck in that was more than 2 hours. even as a daily driver, I took my truck if I went more than 10 miles! with NOTHING left to check, I decided to throw a set of stock offset rims on as a last ditch effort. borrowed a pair with 'closer' offset and noticed an improvement before leaving the parking lot. my test drive was from the shop to my house to order two rims with correct offset. installed today and all is good. a relaxing drive at 80 mph with one hand where 60+ was 2 hands and certainly not relaxing! while my days of towing the pop up at 100 are gone, going 75 like everyone else and not needing to decompress after an hours drive makes it a daily driver once again.

glad to hear that john. see ya at butler,

I like the look of big's and little tires but on my Van I have matching rims and tires all around because that's how it drive's the best.

dix wrote:glad to hear that john. see ya at butler,

butler is 20 minutes and no interstate, I can make that on flat tires. Cortland was an hour and it was enough for me to rule out any more interstate driving. missed quite a few events as it just wasn't worth the drive.

Russell wrote:I like the look of big's and little tires but on my Van I have matching rims and tires all around because that's how it drive's the best.

wasn't about width or diameter, it was centerline of the front tires. the way I understand it, being off center puts more force on the outer edge pushing it back, so wheel turns that direction. the other wheel does the same so you would think they cancel each other. they don't! it follows whichever wheel has the most weight at that moment in time. it didn't shimmy or shake, it just felt loose and not in control. it is still a huge brick on a straight axle but MUCH better with correct offset. original is zero offset, I had -17 mm. the test rims were still -14 (hardly any difference) but made a noticeable difference. I now have -2. with suitable rims, I could run the wide fronts provided I added the same amount inward as I did out.

Yes, rims heavily offset to the outside basically pull on the steering, following grooves, ruts, or whatever..... enough that positive caster doesn't really compensate..... Also increases chances that the tire will contact the front and back of the wheel well when turning.....I like tall, fat tires on the back and somewhat wide on the front, but only as much as a near 50/50 offset and well clearance will allow!

AzDon wrote:Yes, rims heavily offset to the outside basically pull on the steering, following grooves, ruts, or whatever..... enough that positive caster doesn't really compensate..... Also increases chances that the tire will contact the front and back of the wheel well when turning.....I like tall, fat tires on the back and somewhat wide on the front, but only as much as a near 50/50 offset and well clearance will allow!

I had 11 degrees and still wasn't enough! factory shims back in and just under 7 now. I prefer a heavy castor so will bump it back up some day when I am bored, just not today. it just handles too nice to mess with it and still amazed the difference the offset made!

Glad you chased it down and can drive it now!
Another thing the offset wheels do is put extra strain on the smaller outer bearings, causing much more wear. This also happens on rear axles where a big offset will accelerate outer bearing wear. Note the Green line in the pic below.

An additional problem is scrub radius
https://www.hotrod.com/articles/0902sr-science-of-straight-axles/#0902sr_07_z-science_of_straight_axles-direction_of_thrust
(entire article)
https://www.hotrod.com/articles/0902sr-science-of-straight-axles/

This is what causes wide tires to be even harder to turn when stopped. Instead of the inner portion and the outer portion of the tire to spin around the center of the contact patch, the tire is swept in an arc around a spot at the inside edge of the contact patch. The Red line in the pic. Left is stock offset, middle (right without clicking on pic) is wider, offset wheel.

yes, much easier to steer at low speeds or even when not moving at all. surprisingly, there is very little info on this. googled offset, backspacing, king pin angle and scrub radius. must of asked 100 people and two actually agreed it "could" make a difference. even after just buying the new rims and tires, more than half argue it wasn't the issue! maybe it was the new lug nuts? either way, huge improvement and back to being a daily driver.