Dr.Jeff
True Classic
True that a soft spring will compress more than a stiff spring under the same conditions, and that may be an issue on a lowered car....or not. Because there are several variables to consider; wheel/tire size (as you mentioned) and fender lip mods will play a huge role in fender clearance, road/driving conditions affect how much travel is needed, same for how far the car is lowered, the desired level of comfort vs performance you are looking for (always a trade-off), the dampener setting (inside the coilovers), the type of bump-stops, the set up for rest of the suspension, personal opinion for what is considered "soft or hard", etc.Why change springs etc if you're not looking for a performance increase? In my opinion the standard spring rate is way too soft, at least if no front sway bar installed. If you are planning to lowering the car (for improved performance and better looks) I think the MWB recommendation for street cars is too soft. There is a big risk that springs will bottom out and wheel hit fenders on bumpy roads. Of course this also depends on tire size/width and ET.
This happened to me with D2 circuit springs, no rubber stoppers and no antiroll bar (185/60 13 tires):
View attachment 41300
No big damage. It was easy to have the fender straightened, but will need some paint. I am thinking about having even harder springs in the front and maybe a sway bar.
However those springs rates noted earlier are still stiffer than stock by roughly 20%, so they will provide some performance increase - approximately equal to most "sport springs" or "lowering springs" offered for stock struts. And they will offer a nice ride if that is the goal. So depending on all the variables at play, those rates can be a good starting point. Personally, when I was much younger I set up my street cars much firmer than I do now. Therefore 175/225 works for me now, but it will be different for others.