Backspace/offset for wheels on my 1964 GT Hawk

Hello Tom

Depends on the program people use and the options selected whether or not the reply goes to you, the newsgroup or both. You need to check the newsgroup anyway - This is where the action is.

I will let the experts address the wheel questions.

A change to different size tires will throw your speedometer off, so larger rims (unless you are running gumband tires) will certainly affect your speedo readings.

Mark (not completely ignorant, but close) Dunning

Tom, You can get some pretty meaty tires in the rear wheel wells, but you'll need a fairly deep backspacing (5 1/2-6"?), or a narrowed rear, to make it work. I recollect the standard backspacing available in the Torq Thrust line makes it difficult to get much tire inside with a standard axle. Your tire shop should be able to put the car on a rack and do some measuring to determine ideal backspacing/tire size. The speedometer will be effected if you change the overall diameter. Since newer tires are lower profile, you might possibly end up with the same diameter even with a 16" wheel but, again, you have to get out the measuring tape. S2DSteve

you need a front wheel drive offset in the rear and a rear wheel drive offset in the front to run killer tires.

do you want to run the same size wheels/tires front and rear? or do you want as big as possible at both ends?

nate

Someone posted this for the group a while back. It's helpfull.

size were the origonal '64 Hawk GT wheel and tires. Were they195/75/R15s on a 5" rim? I beleive that was the size for '62 Hawks.And here's a question for the Stude faithful. What was the originalwhite wall size for a '62 Hawk? They don't look really huge in the oldphotos. Maybe a inch and a quarter. The off white wheel paint thatshows around the hub caps kind of added to the white on the tire. Tony in Austin

original would have been 6.70-15 on a 4.5" rim, or 5" rim if equipped with the optional "Avanti" wheels (standard on a "super" package car)

I am running 15x7" with 3/4" offset on my '55 coupe (same body) and it works fine, but you could go bigger in the rear if you really wanted to, all the space is on the inside though. That is why I asked above if he wanted to keep the same size wheels front and rear because I think 7" is probably about the max for the front, and certainly the max you can get without playing with different offsets front and rear. I am running 1/4" spacers on the front wheels to keep the tires away from the tie rod ends but even though it is close I saw no signs of contact without them with 215/60s

nate

Yes, I want to run the same size all the way around, so they can easily be rotated. I'm sorry I failed to mention this in the first posting. One more question,. Will the rear axles be adversely affected by larger tires? I've read the OEM axles are not all that strong, and now that they're over forty years old, I don't need to put any more stress on them. I don't want to go to the expense of up-grading, and yet I want to drive te car as often as possible, mostly on extended road trips. As usual, I appreciate all the help. Tom

Thanks Mark. Tom

Thanks for the reply. I appreciate it. Tom

Thanks for your reply. I appreciate the help. Tom

Yes, I do want to run the same size tires all the way around. Sorry I didn't put this in my first posting. Eagerly awaiting your reply. Thanks in advance. Tom

Thanks for this helpful info. Tom

Thanks for the info. I'll carefully consider all my options, and when I get these wheels, I'll let everyone else know, too. Tom

Personally, and this is just my opinion, I wouldn't go too nuts on the tire size. With the wheels mentioned in my previous post, you can run

205 or 215/70 without any problem. You can even fit up to a 245/60 but I don't know if you would really see any benefit from them unless you had some other performance mods as well. For ease of steering I wouldn't go past a 215 on a regular driver, remember that increased effort at the wheel also means increased stress on tie rods, reach rods, etc. etc. etc. I suggest a 70 series tire just because most "sporty" tires aren't available in a 75 series.

It looks like the 15x7 torq-thrust original is only available in a 6mm offset which ought to work on a C-K with 215s but if you think you might want to go with wider tires you probably want to think about going with a custom offset, maybe 13mm or so, or 18-20mm if you are not opposed to using spacers on the front. I seriously doubt that the 6mm offset would work at all on a Lark.

If you are concerned about the axles breaking, peace of mind can be obtained from Fairborn Studebaker; the axles they sell are made by Moser and should be strong enough for most any Studebaker. Not dumping the clutch from a dead start and not speed shifting also help :) (but where's the fun in that?)

nate

d'oh. just looked at the catalog again and it's *negative* 6mm offset... which you probably don't want.

nate