Wheels / Tires: Tire sizes... again

[mjeansonne]

I am presently running 195 75R15 tires on the Hawk and of course they were purchased at least 6-7 years ago, but they still have a lot of tread left. I probably have not driven more than about 3000 miles on them, if that much!! At highway speeds I get some front end rumble which I suspect are coming from the tires being old. I have experienced such rumble on a modern brand x car and that was the problem, old tires!! Also the speedometer seems to be about 5 mph higher than actual mph. What size should I go to? Using more modern wheels doesn't bother me if I need the wider rim, because of unavailable tire size. I so want to use radial tires and I also want more accuracy with the speedometer. What is recommended and what has been everyone else's experience??

[Dan White]

I am using 215 70R15s for 18 years now. Some will recommend 205s which are OK too.

[Skybolt]

What I recommend is do a bit of research as to what your numbers are first. Meaning, what transmission are you running, auto and manual will give you a one to one top gear ratio but an overdrive will be a percentage of that. Your rear axle ratio and the original tires your car came with from the factory. This will all be easy if the car is stock and it's only the tire size you need to know. Once you have this information there are websites that have old tire sizes and corresponding new tire sizes. I did this with mine so I could find a tire size of 26". I was going wide and used a 235/65 x 15. But I had my wheels custom made with my specified offset. I would, in future, for ease of mind just go with a standard after market or factory rim and get some 205's. I don't need to stay with that tire size because I know what all the numbers mean and can now swap one or as many as I like and match the speedometer gear to suit. That is the hardest piece of the puzzle to some times get so for speedometer accuracy you might be dictated to by it.

[52hawk]

I have 205/75/15 's on the front,215/75/15's on the rear. All on 15x6 wheels,with 3.5 inch backspace,on my 61 Hawk. I like it because the wheel wells look 'full' looks like stock sized tires,and 205s on the front may be just a bit easier to steer.

[whacker]

I have 205-75R15 mounted on 1970 Ford Galaxie disk brake wheels. Backspacing is 4 inches, width is 6 inches. The speedometer is correct (within reason).