16.5 inch rims thinking of changing
I have an old Dodge Motor Home. The Engine is a 1978 440, the chassis is a 1979 Dodge MB400 and the Body is a 1980 Automate Mini. This has been a pain to work on, but got it on the road after replaci...
Forum Discussion
Barry's Tire Tech is an OP here called capriracer. He offers information about the switch.
He discusses Dually Spacing, also called Offset. There are Offset specs in his info, but not an illustration of it. Drawings aren't so easy to find, but I'll look and post what I can find. The spec "offset" is NOT the distance between the sidewalls. That distance results from the wheel offset (aka dually spacing) and the tire size and profile. Being able to determine the offset, then using Barry's chart, saves you from getting tires and wheels only to mount them up and find there isn't enough sidewall distance..
All Right Then! This should cover Spacing/Offset for you
The "Dual Spacing", taking in BOTH rims, is the Offset Spec, and you can take that to Barry's chart. If you have one wheel, you can lay it on its flat center and measure to the CENTER of the Rim, between the two BEADS, NOT the low spot you see in the above pic. In other words, from what would be the dead center of the tire's TREAD once mounted. That measure is HDS (Half Dual Spacing) and you'd double that, look at Barry's chart, and be able to tell if your tires will mount on the wheels you're looking at. WITHOUT being too close!!! If they appear separated at rest, they can still bulge from dips in the road. If those sidewalls get to "kissing" they WILL destroy the tires.
He discusses Dually Spacing, also called Offset. There are Offset specs in his info, but not an illustration of it. Drawings aren't so easy to find, but I'll look and post what I can find. The spec "offset" is NOT the distance between the sidewalls. That distance results from the wheel offset (aka dually spacing) and the tire size and profile. Being able to determine the offset, then using Barry's chart, saves you from getting tires and wheels only to mount them up and find there isn't enough sidewall distance..
All Right Then! This should cover Spacing/Offset for you
The "Dual Spacing", taking in BOTH rims, is the Offset Spec, and you can take that to Barry's chart. If you have one wheel, you can lay it on its flat center and measure to the CENTER of the Rim, between the two BEADS, NOT the low spot you see in the above pic. In other words, from what would be the dead center of the tire's TREAD once mounted. That measure is HDS (Half Dual Spacing) and you'd double that, look at Barry's chart, and be able to tell if your tires will mount on the wheels you're looking at. WITHOUT being too close!!! If they appear separated at rest, they can still bulge from dips in the road. If those sidewalls get to "kissing" they WILL destroy the tires.
