Tire Size Change and Speedometer difference?

[vacationtime247]

Came home last night from work and had to go back out again. Found one of my tires were flat. So, this morning I went and replaced 3 of the 4 tires. The 4th was a good used one so I didn't bother, plus I'm cheap. Nevertheless, found a deal on new tires for $58 each, total for 3 new mounted, balanced, installed and tire disposal fee was $185. Not bad. But upon closer inspection the new tires were of a different size. The back tire has the different sized tires. This going on my Diesel Tempo

Factory size was 185/75/R14 New tire size is 195/70/R14. What difference is there in MPH? Think I'll notice any change in MPG? Just curious so I'll know how to calculate for the difference in mileage upon fillup.

Fly out today to purchase my house in California, so if I don't respond quickly I'll go ahead and thank y'all in advance for the answer.
VT247

[RobertISaar]

Tire Size Calculator - Discount Tire Direct

that should help you out. total of a .7% difference. i would attempt to keep the odd pair on the non-driven axle, otherwise constantly differing tire speeds could play havoc on you differential. with this small of a difference, i don't think you'll see much difference though.

[Frank Lee]

.7% might fall within the range of manufacturing tolerances for any tires of "the same size".

BTW I was just shopping for tires too- had quite a few cords hanging out of a lumpy tire on the T-Racer (extracted the last mile outta that sucker!) found some nice Guardsman (Cooper) tires at Sears for $46 each; brought them elsewhere for M+B for $20 total. They are 185/70s vs 185/65 stock; I put them on the front for a 3% "overdrive".

[HypermilerAX]

Originally Posted by RobertISaar

otherwise constantly differing tire speeds could play havoc on you differential.

Don't think it's a problem with such a small difference. 0.7% is the difference between a new tire and a 25% used tire of the same size. The differential is always moving, even with the same tire size.

[vacationtime247]

Thanks, didn't think there would be much difference. Time to go west.
VT247