Stock tires size for a 75 olds

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October 30th, 2019, 05:32 AM

midnightleadfoot

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Join Date: May 2017

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Stock tires size for a 75 olds

Cutlass salon?
From what I can find it looks like it was HR70-15"
is that correct?
and if so, does that cross to a 235-70-15?
Thanks.

October 30th, 2019, 07:38 AM

svnt442

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Location: Palm Bay, FL

Posts: 4,249

That looks about right from the crossover information that I could find.

October 30th, 2019, 08:43 AM

oldcutlass

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HR70-15 was 28.1 inches in diameter, 235- 70R15 is 28 inches in diameter

October 30th, 2019, 08:51 AM

damaged442

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Location: The Cuse, NY

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I run a 225/70/15 on my 77 Supreme with SSIIIs, which is what I thought the best cross reference equated. On my 87 442 and 87 GN with 15" wheels, I run 235/60/15.

Both sizes will work well and should not have any rubbing, or mess up your speedometer.

October 30th, 2019, 05:30 PM

joe_padavano

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Location: Northern VA

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A 1975 Salon could have come with GR78-15, G78-14, HR78-15, or HR70-15 tires. The ODs range from 27.06" for the G78-14s to 28.36" for the H78-15s. 235/70-15s would be the closest match for the HR70-15s. The 225/75-15s would be best for the HR78-15s and 225/70-15s for the GR78-15s.