New Tires ---HELP PLEASE !
Thread Starter
Racer
Joined: Mar 2005
Posts: 275
Likes: 21
From: North Carolina
New Tires ---HELP PLEASE !
I just replaced the original Goodyears with Michelin Pilot Sport A/S Plus ZP. I just traveled to our vacation home on the new tires and I know for a fact, past 3 cars, that it is exactly 189 miles from drive way to drive way. When I got to our vacation home I checked the trip milage and it was 181 miles! Something is very wrong here.
I checked tire rack . com and the OEM goodyears spec out as follows.
Revs per mile front 17" tires , 814 rear tires 18 " 781
Michelin tires:
Revs per mile front 17" tires 810, rear tires 18 " 780....
What could make up the difference between the 189 miles on the OEM Goodyears and 181 miles on the new Michelins ?
HELP !!! PLEASE !!!
I checked tire rack . com and the OEM goodyears spec out as follows.
Revs per mile front 17" tires , 814 rear tires 18 " 781
Michelin tires:
Revs per mile front 17" tires 810, rear tires 18 " 780....
What could make up the difference between the 189 miles on the OEM Goodyears and 181 miles on the new Michelins ?
HELP !!! PLEASE !!!
Team Owner
Joined: May 2001
Posts: 87,334
Likes: 1,590
From: Western NY
I just replaced the original Goodyears with Michelin Pilot Sport A/S Plus ZP. I just traveled to our vacation home on the new tires and I know for a fact, past 3 cars, that it is exactly 189 miles from drive way to drive way. When I got to our vacation home I checked the trip milage and it was 181 miles! Something is very wrong here.
I checked tire rack . com and the OEM goodyears spec out as follows.
Revs per mile front 17" tires , 814 rear tires 18 " 781
Michelin tires:
Revs per mile front 17" tires 810, rear tires 18 " 780....
What could make up the difference between the 189 miles on the OEM Goodyears and 181 miles on the new Michelins ?
HELP !!! PLEASE !!!
I checked tire rack . com and the OEM goodyears spec out as follows.
Revs per mile front 17" tires , 814 rear tires 18 " 781
Michelin tires:
Revs per mile front 17" tires 810, rear tires 18 " 780....
What could make up the difference between the 189 miles on the OEM Goodyears and 181 miles on the new Michelins ?
HELP !!! PLEASE !!!
FWIW, I had 3 cars, the same route to work, and all 3 odometer readings were different...
Thread Starter
Racer
Joined: Mar 2005
Posts: 275
Likes: 21
From: North Carolina
Over the years, last 30 years, the milage to our vacation has always been in the range of 189 give or take a mile or two depending on the car. When my OEM Goodyears were brand new it showed 189 miles and now with the new Michelins it is showing 181?
Le Mans Master
Joined: Oct 2005
Posts: 7,286
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From: Texas Where God intended me to be.
2023 Corvette of the Year Finalist - Unmodified
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St. Jude Donor '08 thru '11,'22 thru '26
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I take it you changed tire size since the rotations per mile are different. No matter the brand the tire circumference should be the same for a specific size tire. When I changed tire size I had the my tuner put the new size in the system that way the speedometer was right as well as the odometer.
I take it you changed tire size since the rotations per mile are different. No matter the brand the tire circumference should be the same for a specific size tire. When I changed tire size I had the my tuner put the new size in the system that way the speedometer was right as well as the odometer.
Last edited by Grumpy; Jul 5, 2010 at 11:42 AM.
Thread Starter
Racer
Joined: Mar 2005
Posts: 275
Likes: 21
From: North Carolina
Yea some people on here are well I won't step down to their level.
I take it you changed tire size since the rotations per mile are different. No matter the brand the tire circumference should be the same for a specific size tire. When I changed tire size I had the my tuner put the new size in the system that way the speedometer was right as well as the odometer.
I take it you changed tire size since the rotations per mile are different. No matter the brand the tire circumference should be the same for a specific size tire. When I changed tire size I had the my tuner put the new size in the system that way the speedometer was right as well as the odometer.
Drifting
Joined: Jan 2008
Posts: 1,722
Likes: 138
From: Florida
St. Jude Donor '09
Obviously not as shown by the distance reading on your odometer. Assuming your readings are correct, your rear tires are slightly taller than the originals.
It is not uncommon for tire's diameter, width and circumference to vary slightly among manufacturers given the same size tire.
It is not uncommon for tire's diameter, width and circumference to vary slightly among manufacturers given the same size tire.
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Melting Slicks
Joined: Jul 2006
Posts: 2,332
Likes: 31
From: Silver Spring MD
I put PS A/S ZPs on 3 years ago and never looked back
I couldn't believe the ride and road noise difference for the Michelins and the GYs. If the tires are slightly larger in diameter so what.
Are you calibrating your speedometer/odometer for police chase use?
Seriously forget the slight mileage difference and enjoy the ride.
Are you calibrating your speedometer/odometer for police chase use?
Seriously forget the slight mileage difference and enjoy the ride.
Burning Brakes
Joined: Aug 2005
Posts: 772
Likes: 6
From: Huntsville AL
Same tire size from brand to brand will be slightly different in overall diameter due to tread depth and hardness/softness of compound. That is why if you look at 5 different tires of the same size on tirerack, they will have a slightly different overall diameter/rev per mile.
Check your speedo and odometer against a GPS. If needed, you can have the computer reprogrammed for your new tires or you can buy a programmer that will do it.
Check your speedo and odometer against a GPS. If needed, you can have the computer reprogrammed for your new tires or you can buy a programmer that will do it.
Former Vendor
Joined: May 2000
Posts: 4,776
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From: 877-522-8473 ext. 4362
St. Jude Donor '11-'12
slight variations in design, materials, and manufacturing can allow for more or less sidewall deflection whihc in turns alters the "static loaded radius" of a tire. 2, 3 or even 10 revolutions per mile has a nominal effect on your speedometer and odometer.
A tire's static (not moving) radius is only accurate while the vehicle is stopped. A static loaded radius is typically about 44% of the static loaded diameter. As the vehicle speed increases, centrifugal force causes the tire to grow taller. This force will increase the tire's dynamic (changes while moving) radius. At 45 mph, most tires will have a radius that is very close 48% tire's static loaded diameter. This growth will increase with vehicle speed and can actually exceed half of the tires static loaded diameter. The static loaded diameter is NOT the same thing as an static unloaded diameter.
A tire's static (not moving) radius is only accurate while the vehicle is stopped. A static loaded radius is typically about 44% of the static loaded diameter. As the vehicle speed increases, centrifugal force causes the tire to grow taller. This force will increase the tire's dynamic (changes while moving) radius. At 45 mph, most tires will have a radius that is very close 48% tire's static loaded diameter. This growth will increase with vehicle speed and can actually exceed half of the tires static loaded diameter. The static loaded diameter is NOT the same thing as an static unloaded diameter.
Advanced
Joined: Feb 2005
Posts: 85
Likes: 0
From: Myrtle Beach SC
My pickup will vary greatly depending on tire pressure...I discovered this because I was getting passed by everyone. Before I bought a GPS. The Speedo and the Odo were registering 3.5 MPH faster and more traveled than actual. Took the truck ( At dealers expence to a shop with a Police certification Dyno ) They wrote down and signed all the differences at speeds. Since most cars/trucks average 35 mph, The dealer agreed to add that amount of coverage to my warranty. I also played with TP while there and got significant changes up to making the reading right.....I just wasn't willing to deal with the ride quality at that pressure.
Since then I have owned at least 4 other GM vehicles.....All read just about the same error.
Since then I have owned at least 4 other GM vehicles.....All read just about the same error.