why the change in factory tire size?

[am not r2]

At some point Studebaker went from 7.10 to 6.70 (on Hawks anyway). Any one have a guess why? Just curious.Rich

[BobPalma]

At some point Studebaker went from 7.10 to 6.70 (on Hawks anyway). Any one have a guess why? Just curious.Rich

No need to guess, Rich: the tire size specified, at least back then, was based on what the engineers thought would be the gross vehicle weight of the car, loaded per the design parameters.

Today, darn near every make, year, and model of car has its own tire size due to fuel mileage and handling characteristics being thrown in the mix. That has to be one reason for today's exorbitant tire prices; with so many sizes, the economy of scale in making "X" number of tires for the replacement market is greatly reduced, as opposed to how many gazillion tires of a given size they could crank out back in the day when there were far fewer sizes to serve the replacement market. BP

[Hawkowner]

I would bet it was 3 or 4 cents a tire cheaper.

[StudeRich]

With the Longer, Lower Look started by Chrysler in back in 1957, I would think the other Auto Makers were trying to catch up to that Fad and make them look Lower as Studebaker did in 1958 with smaller diameter 14 Inch Wheels and Tires, so that could be one reason.

[studegary]

At some point Studebaker went from 7.10 to 6.70 (on Hawks anyway). Any one have a guess why? Just curious.Rich

I really do not understand the premise of this question. For example; for 1957, the second year of Hawks, Silver Hawk 6 came with 6.40-15, Silver Hawk V8 came with 6.70.15 and Golden Hawk came with 7.10-15.

[studegary]

For some reason, what I posted this morning did not show up as a new post or that I had made an entry on this topic.

[StudeRich]

Yeah, BUT, don't all "Later Hawks" '59-'64 use the 6.70X15's? Maybe that's what is "Meant".

[62champ]

Wonder if one could order 7.10x15 if you wanted? Have seen a couple T-cab production orders where, instead of the standard 6.70x15, 7.10x15 was ordered and another that was ordered with 8.00x15 Firestone 500s...

[RadioRoy]

Remember that the tire size designation changed at some point. IIRC, an early 6.70 was larger diameter than a later 7.10 or something like that. That's just before we got into letter sizes.

[studegary]

Yeah, BUT, don't all "Later Hawks" '59-'64 use the 6.70X15's? Maybe that's what is "Meant".

Only the Golden Hawks used the 7.10-15 and there were no Golden Hawks after 1958.
I think that the original poster may have, or have been referencing, a Golden Hawk with 7.10-15 and assumed that all earlier Hawks had 7.10-15, which was not the case.

[8E45E]

Only the Golden Hawks used the 7.10-15 and there were no Golden Hawks after 1957.

I think you know better than that!!!

Craig

[studegary]

Wonder if one could order 7.10x15 if you wanted? Have seen a couple T-cab production orders where, instead of the standard 6.70x15, 7.10x15 was ordered and another that was ordered with 8.00x15 Firestone 500s...

Trucks are not analogous to cars in that trucks normally had many different operating equipment, as opposed to creature comfort, options.
For example, for 1957 there were no optional tire sizes for Hawks (just the three different standard sizes).

[studegary]

I think you know better than that!!!

Craig

Of course I do. My excuse is that I was concentrating on 15 inch tires. The 1958 Golden Hawk had 14 inch standard and 15 inch optional.
1958 Hawks had a similar situation to 1957s, except a little more confused due to 14 inch and 15 inch. 1958 Silver Hawk 6 still had 6.40-15 standard and 7.50-14 optional at extra cost. 1958 Silver Hawk V8 had 7.50-14 standard and 6.70-15 optional at no extra cost. 1958 Golden Hawks had 8.00-14 standard and 7.10-15 optional at no extra cost. (1958 Packard Hawks had 8.00-14 standard and had no option.)

[Blue 15G]

Back to Bob Palma's remarks about the proliferation of tire sizes: About 20 years ago my Aunt needed new tires for her car (don't recall which of her cars anymore, but it wasn't *THAT* old), and the guy at the tire shop said they had to order them in the next day. When she questioned why this could be, the guy said that the new cars don't use that size. To which my Aunt said: "New cars don't need tires!" The guy couldn't come up with a comeback to that one!

[studegary]

Back to Bob Palma's remarks about the proliferation of tire sizes: About 20 years ago my Aunt needed new tires for her car (don't recall which of her cars anymore, but it wasn't *THAT* old), and the guy at the tire shop said they had to order them in the next day. When she questioned why this could be, the guy said that the new cars don't use that size. To which my Aunt said: "New cars don't need tires!" The guy couldn't come up with a comeback to that one!

I don't know about "About 20 years ago...", but in the 1960s, when I bought new cars every year, the original equipment tires lasted about six months (15-20K miles).