Tire, speedo question


Old 09-07-04, 08:59 AM
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Join Date: May 2001
Posts: 516
Tire, speedo question

Last time I retired my Buick Century, 93, 3.3 I had original type tires on it 185-75-14. I put on 205-70-14s on it and the ride is much better and it handles better. The speedo seems fast and I imagine it is. Is there a formula that will tell me what degree my speedo is off? The original tires are about 1 1/2 inches taller than the replacements.
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Old 09-07-04, 02:53 PM
Join Date: Apr 2002
Location: Pittsburgh,Pa
Posts: 2,417
A 185/75r14 is equivilent to a 195/70r14 in height.A 205/70r14 should be taller than the stock 185/75r14 resulting in the spedo reading SLOWER than actual speed not faster.How did you measure the tires.
Old 09-08-04, 12:01 PM
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Join Date: May 2001
Posts: 516
I measured the tires on the rim with a ruler, the 70's were 1 1/2 inches shorter than the 75's
Old 09-15-04, 08:36 AM
jatco's Avatar
Join Date: Mar 2004
Location: Vancouver, BC
Posts: 1,045
Try this....
1.5% too slow.. So if your speedo reads 60mph youre actually doing 60.9mph. Dont think you'd get a ticket for that difference...j/k

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