I wonder if someone could answer a question about the optional aluminum wheels that came on my 2007 190V Roadtrek, which has 7" wide wheels? I am planning on installing LT 265 MICHELIN Agilis CrossClimate on my vehicle. I understand that my wheels may have a different offset than the steel Silverado steel wheels. Is there a problem and what is the problem with using this aluminum wheel? If it is required to go to a steel wheel, what year Silverado do I look for? Thanks in advance
This is the Cliff's notes version on the discussion about offset, but there are lots of further details in many discussions here on the forum.
I assume you know that offset is the distance from the centerline of wheel to the centerline of the tire. Positive offset moves the tire inboard and negative offset moves the tire outboard of the wheel centerline. The OEM van wheels are +28mm so the tire is move inboard of wheel center to get the tire in the right position to rotate in the designed arc around the balljoints when you turn and center the tire between the two front wheel bearings. These dimensions determine the scuff radius, which is best to look up the definition and pics for, and scuff radius is what keeps the tires from scuffing and dragging on turns. Changing offset changes scuff radius so can cause scuffing and loss of traction in turns.
The other thing is that the offset/ball joint relationship determines how far the tires move for and aft as you turn. Less positive/more negative moves the tire outboard and make it move more for and aft so more likely to contact the front or rear wheelwell or lip.
The stock steel wheels on the vans are +28mm offset and the AR aluminum wheels that Roadtrek put on are -6mm offset, so the tires move out about 1 3/8" on each side. This is a lot of offset change and will make the tires scuff. It can be especially easy to see if you back up on clean concrete and turn sharply a few times. You will leave tire marks all over the concrete from the scuffing/dragging. Our driveway would look like we had a burnout contest after I backed into the hard to line up garage. I changed to stock offset +28mm wheels to get the7" width needed for the 265 tires and no more tire marks, none at all.
The particular Silverado wheel is about the only correct offset wheel available in wide enough for the 265 tires, AFAIK, in 16" size. You can get a factory Silverado wheel that is wide enough and correct offset in 17" but you give up some load capacity compared to 1". They are aluminum, so a possibility if that is important. You go to 265-70-17 tires on them which have the same rolling radius as the 265-75-16 tires.
As to your case, it might or might not clear the fender lips with the 265 tires and AR wheels. Variations and tolerances are pretty loose on the body on frame designs so the front and back gaps from the wheel well lip to tire can vary a lot. On our 2007, they probably would have not hit on the left front, but would have hit on the right front rear off the wheel well.
It is a tough choice and many find it hard to give up the nice AR wheels for a plain steel wheel. Others want to get back to the best steering and handling geometry they can, and reduce wheel bearing load by getting factory offset wheels. I am in the second category, and would not go back to the big negative change in offset but others would not see it the same way. If increasing load capacity is not the major concern, the 17" aluminum Silverado wheels might be a good compromise.