Tire to fender clearance - how close is too close?

[Spyder]

How much tire to fender clearance do you need for the rears? I plan to order new tires in the next day or two and I love the look and stance of my car currently, but the passenger side rear is uncomfortably close to the fender. I can fit my fingers in the gap, barely, but can't move them.

The rub marks on the tire are from the old fender that was crumpled in a bit, they haven't rubbed since the bodywork and paint was done but I suspect they would if I ran low on air on that side. Drivers side has a little more clearance and I can pass my fingers through, while touching both tire and fender, they'll still pass through.

These are 275 60R15. Do I need to go down to 255 60R15?

 

[pschlosser]

I would say 1/2 inch is the minimum on the front and rear. In the front, there is plenty of room in the wheel well for it to travel upward, so there, it is the up movement while making a turn that can be an issue, and 1/2-inch at rest turning fully left an right has proven reasonable in my experience.

Regarding the back, very much the same. 1/2-inch clearance. You maybe can push it to 3/8-inch. 1/4-inch runs the risk of rubbing at high speeds and causing a blow out. The AAR and T/A had (most of them, I think) "rolled" fenders, wherein the lip shown in your pictures was brutally rolled up and inward at the factory by using a length of 2-inch pipe (more or less) Of course, this was done only to the front fenders, if I recall correctly. But I've seen others doing it to their rears more than once.

Over the years, I've pushed my luck. I would run wide tires on 14 x 5 steel wheels. This causes the tire to balloon outward at the sidewall. On a long turning curve at high speed, as the side G-forces move the axle and wheel outward (while the tread stays put, more or less) and the car undulates up and down you can experience some side-wall rubbing. I recall hearing it a number of times. I've never had a blow out occur, but the paint at the top of the inner wheel well lip was buffed off down to shiny metal.

In your pictures, especially those depicting your hand, I think I see evidence of rubbing on the sidewall of the tire. So you're already at the threshold. If you want to keep those tires and want more clearance, you may need to roll the lip upward, as described by the factory procedure above.

Inspect how much space you have from the inner side wall to the leaf springs. If you have, for example, a full-inch in there, in theory you could change to a lesser offset wheel without the need to roll the lips.

Rolled lips don't show, but your paint job looks beautiful, and there is a risk of cracking the paint at or near the lip where is DOES show.

Once when servicing the leaf springs, I lowered the car to see how far down (or wheels up, as the case may be) things go, before the pinion snubber kicks in. It was educational, and in my case, there was ballooned-sidewall contact.

 

[Xcudame]

If your finger tips are like mine and you can put them all along the wheel lip and tire like shown in your first photo, you're good to go. You have discovered one thing I like to mention is that our cars can have a lot of variance from side to side. I've seen up to 1/2"!