255’s or 235’s on 15×7 Ralley IIs

Q: 255’s or 235’s on 15×7 Ralley IIs

Does anyone know if 255 70 R15’s or 255 90 R15’s will rub on 15x 7 Ralley II’s if I put them under my 1968 Firebird 400 car? I know I’ve heard much about this in the past.But just cant recall.

A: I’ll assume that the above “255 90 R15” is really 255 60 R15. A 90 series tire would be very tall and skinny indeed.

What will fit will depend partially on how much, if any, your car sags in the rear, or has been lowered in any way. So a simple answer is difficult to offer that would be accurate in any way.

Here is how the tires stack up in diameter:

As you can see, the 70 series tires are noticably taller than the 60 series tires, and some of these sizes are more than 3.5″ taller than the stock tire. You need to check your present clearance to see if you can fit tires these sizes as your car sits now. Air shocks will of course get you more clearance, but they have their own problems and I would not reccommend their use.

Up front, many owners run 225/60 or 70-15s, and I run 235/60-15 without problems. others report rubbing with some of these sizes. I get a little rubbing on steep or off-camber driveways. I think that a 255/70 or 60 in front is too tall and would definately rub unless your car sat very high. At least one member reports running 245/50-15 up front, and he can tell you about what problems if any he’s encountered. I find that this is too wide for my car with my present offset wheels. That’s a 7 inch Ralley II.

In back, members have reported running 255/60s without much trouble. I think that a 7 inch wheel my be too narrow for this tire and will not allow the tread to fully meet the road surface. Excessive wear in the middle will result, and you will not get the full effect of this width tire. An 8 inch wheel will be much better. An offset of 4.5 inches should allow you get that tire inside the wheel well, though at 27 inches tall, you need to check for adaquate clearance.

A: Been several posts in the past on this Biggest size on an unaltered 67-9 is 235-60 x15 on 8 in wheels G has 225s on 8 in snowflakes,I used 235s on 7 in snowflakes tried 245 on 8 in snowflakes and was too big.

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