I’ve seen some 18” redline wheels but they say there are 19” ones also. Anyone seen one? Specs say 245/50/18 7.5x18 ET 38 and 245/45/19 8x18 ET 35. both OD is 27.7” And backspacing is pretty close. Inner clearance is 3 mm less and outer is 8mm extended.
Gabriel makes an ultra strut for equinoxes that says it’s for 19” “cars” and I wonder how they differ from non 19” cars? I assume a 18” wheel would then fit ok? They would have “more” clearance from rim edge? I know equinox and vue are related so my question might seem odd. Oh, the 19” ones are on sale at Rockauto for $40. This is strut assy. Includes springs/mount.

 

Second generation Vue 2008 on, I'm assuming.

In my limited suspension experience, if a product is spec'd for a particular configuration/application, it's usually for a good reason. You seem to understand the concept of offset; many do not.

The struts for the vehicle in both cases must mount at the top and mount on the hub, so obviously they can extend and must extend to the correct length. However, I suspect the spring force and damping to be different. Otherwise there would be no reason to spec a 19-in strut differently than an 18 in strut (wheel size). The different offsets between the wheels you mentioned will obviously affect alignment which would need to be corrected for, at least the 19 in. I don't remember what is standard. My guess is that the 19-in compatible struts probably have less of a spring force equivalent because they assume the vehicle is higher in the air already. Given that you have specified two different size wheels with the same OD is interesting. Obviously the strut can't know the wheel size, but it will be affected in terms of alignment differences as earlier stated.

​​​​​​So the strut for the 19-in is probably softer, and because of that, the car may sit lower at rest as compared to having the 18-in struts on the vehicle with the same tires.

I fully agree this sounds non-intuitive and backwards, as initially, you would think comparing just strut to strut, that the 19 in would, at rest, hold the vehicle higher. However that assumption may be incorrect if the two struts are not identical. I strongly suspect they are not.

I would recommend that you go with the strut appropriately specd for the application of the wheel size that you use.

 

I called Gabriel tech line and was told physically they are almost identical but spring rate is slightly different. I had 235/50/18 tires on previous car and it should have been 235/55/18 so they were 1/2” shorter. I’ve never come across any 19” factory wheels.