cfair

I’m pretty much a trust-the-factory kind of guy. Mostly stock looking 98 and Starfire from ‘66.

Currently running 15x7’s at all 4 corners on my 66 big cars. They are a nice upgrade over 14x6 they came with.

If I have the room, is there an advantage to going 15x8 either just in the rear or all around?

What are are the disadvantages of going staggered this?

I think they’d look better,but don’t want to mess up ride and handling.

Thanks in advance for your thoughts

cf

Lonnies Performance

If they are of reasonable size, where you do not have to lift the car to make them fit, or otherwise have any body contact, it should not have any adverse effect on handling or ride quality.

Wider will give you better dry traction, but will make the car more sensitive to hydroplaning in the rain, but this typically is not significant unless you get into a very wide tire.
Anything that properly fits an 8" wheel should not be an issue.

Adding height to the rear will decrease your gear ratio, which can be good or bad depending on what you currently have/need.
A taller tire can give a less responsive feel during cornering. Considering you are talking about big cars, I doubt you are driving overly aggressive anyway.

The only drawback I see is losing the ability to do a 4 corner tire rotation.

sysmg

I always like wider tires on the rear, especially in a muscle car. Clearly benefits traction off the line. I am planning to upgrade my 66 Starfire tires. Currently have a mixed bag, 235/70-14 on the front original 14x6 amd G60-15 on 15x7 on the rear. Handles quite nicely. I was thinking of doing something like what you are currently running. 15x7 with 255/60-15s all around. I didn't think narrow 70s in the front (probably would have to be 215 on 15" wheels) would handle very well. If you upgraded to 15x8 what size tires would you run in the rear, and what size in the front?

sysmg

I finally pulled the trigger. I upgraded my front rims to 15x6 and got 225/70-15 for the front and mounted 255/60-15 on the rear 15x7 rims. Both sizes are within a few 1/10th of an inch from the original 8.25-14 tires that were 27" in diameter.

Charlie Jones

My advice ,
Larger tires on the rear than the front is OK for drag racing .
But if you want decent handling , keep all tires the same size .

Vintage Chief

I was about to reply then realized this is about a car.

joe_padavano

Not entirely true, but a mid-60s Olds full size will never be confused with a sports car.

Most high-end sports cars today actually do have "staggered" tire sizes (and I really hate that term...). The trick is that even the smaller front tires are not "front runners" like drag cars, they are quite wide. It's just that the rear tires are even wider. For example, the last C7 front-engine Corvettes had 245 front tires and 285 rear.

oldcutlass

There are good points to both staggered and running the same size all the way around. To me its mostly a personal choice. With a B body I can go either way. How about some pictures.

joe_padavano

On my 67 Delta, I've got 235/70s on 15x7 wheels on the front and 275/60s on 15x8.5 wheels on the back. The 275s fill the wheel wells very nicely.

oldcutlass

I bet the 235's do also.

joe_padavano

Height-wise, yes. I specifically picked that combo because the ODs were the same. The 275s fill width-wise also.

sysmg

The wider tires in the rear are not so much about handling. It's about reducing wheel spin on acceleration, mid 60s 425 or 455 equipped full size spun the wheels pretty easily, even unmodified. They might help handling a bit on a long sweeping turn when you have your foot deep into the throttle.