Any idea what tire size would fill the top of the arch better ?

I don’t like that gap above the tire between the arch

I’m thinking maybe going 70 profile like a 255/70/15 ?

Below are pics of it with

15 x 8 (I think)
5” BS
275/60/15’s
1.25” spacer

And I still have a lot of room to spare

The wheels I want I have to decide between

15 x 10 with 4” BS

Or

15 x 8 with 3.75”

It seems my car is a little raised at the rear so I don’t think I’ll have a problem with rubbing on those backspacing but I would just like the gap between the top of the tire and arch to be a bit fuller , that’s why I thought maybe a 70 profile

Thanks

P.S the car is not on the Jack in the pics , I had just lowered it down

To me, the car just looks too high. I'd want to lower it about 2".
But I agree on filling the wheelwell, and not seeing a gap above the tire.
But yes, a 70-series will tend to fill the opening a bit better; but it's likely to be a taller tire.

FWIW: I'm not a fan of what we in the US call a tire-cross; hope you have a proper socket, extension & etc for the lug nuts.

Thanks for the reply

So a 255/70 should fill that gap at the top a bit better ?

I actually really like 70 profile tires from the pics I’ve seen

A 275/60 is about 28" tall, and a 255/70 is close to 30", IIRC.
So, it's about an inch at the top.
I've had 255/70s on 8" wheels, and they looked fine; 10" wheels are probably too wide for them, though.

This.

It’s not the tire. It’s the car. It’s too high.

What’s the easiest way to lower the rear ?

The front sits a little high too though so I guess would have to lower that as well

The pics below , the wheel/tire sizes are

Rear - 15 x 8
3.75” BS
295/50/15

Front
15 x 7
3.75” BS
235/60/15

Thanks

Rear: least expensive would be lowering blocks. You might need longer U-bolts. Optimally it's rear springs with less arch.
Front: torsion bar adjustment bolts, basically unscrew them a bit.
Make sure you leave a gap at the control arm bumpers, though; usually about 1" is OK, as they're inboard of the arc of travel.

In my opinion the 275-60-15 is the perfect "Day 2" muscle car mod. Its height of near 28" and its 11" section width compliment a muscle car- especially the larger bodies like Mopar B body. The 70 series gets too narrow (again- my opinion.) Id run the 275s and try some lowering blocks. You can get a taller tire with the same width as the 275-60-15 but NOT in raised white letters. The Hoosier and MT pro street radials have a nice assortment of sizes but 1- Are insanely $$. 2- None available. 3- Blackwall only.