|09-17-2010 07:19 AM|
According to my GPS, when I ran at 55 mph on the speedo, I was traveling 57-58 mph. That was with 32x11.50's. My stock tires were 30x9.50. When I
changed to 31x10.50's my GPS reads 56 when the speedo reads 55.
|11-10-2009 04:17 PM|
phantom alert review
|10-16-2009 04:50 PM|
|YjPoWeR93||running 33 with stock spedo gear in my yj at 5 mph its dead accurate at 10 its like 2 above and so on till like about 55 then 55 is 64 and thats my jeep running as fast as she can! haha dont ask me why but thats what i have found..|
|10-16-2009 07:49 AM|
|10-16-2009 05:04 AM|
It is after all a small truck!
|10-16-2009 12:24 AM|
|95riogrande||not sure where you read that but ok, thank you. yes larger tires = stock speedo reading slower than actual vehicle speed. its a thread for the people who want to figure out what they might have to change or what changes when upgrading tire size. if you can't figure out the formulas or don't believe they are correct don't use them.|
|10-15-2009 11:35 PM|
|plac||a larger tire makes your speedo run slower, not faster|
|10-15-2009 10:24 PM|
|95riogrande||but yeah it would be off about 5mph at 25mph compared to a stock 27 or 27.5 inch tire to a 32.5 inch tire|
|10-15-2009 10:15 PM|
|95riogrande||didnt realize it re-post or shows each edit when I make changes lol|
|10-15-2009 10:14 PM|
|Vaultzz||And now it reads even more... i'm not quite sure whats going on|
|10-15-2009 10:13 PM|
Honestly I've never looked at it while going that slow.
your post is acting weird. If looking at it on the forum it reads:
|10-15-2009 10:05 PM|
|10-15-2009 09:53 PM|
|10-15-2009 09:51 PM|
|NAVYCHIEF||what kind of TRUCK is this refering to? JEEP TRUCK JEEP TRUCK JEEP TRICK TRUCK|
|10-15-2009 09:48 PM|
|10-15-2009 09:26 PM|
Looking to change tire size? Read me!
Found some very useful info.
Below are some of the mathematical formulas used to answer commonly asked questions concerning fitments of light truck tires.
"How much extra ground clearance under the axles will be provided?" or "How much will it raise the vehicle's center of gravity?"
(New Tire Diameter-Original Tire Diameter) / 2 = Approx. change in ground clearance and center of gravity
(32.5" - 27") / 2 = 2.75" change (increase) in ground clearance and center of gravity
"How will it affect the acceleration performance of the truck?"
The answer is that it has the same affect as changing the axle ratio of the truck.
(Original Tire Diameter / New Tire Diameter) X Original Axle Ratio = Effective Axle Ratio
(27" / 32.5") X 3.50 Original Axle Ratio = 2.91 Effective Axle Ratio
"How will it affect the performance of the truck on the highway?"
(Original Tire Diameter / New Tire Diameter) X RPM@MPH = New RPM @ actual MPH
This example is for 55 MPH
(27" / 32.5") x 2400 RPM = 1985 RPM @ 55 mph with new tires.
"How far off will the speedometer be?"
May be speeding ticket time!
(New Tire Diameter / Original Tire Diameter) X Indicated Speed = Actual Speed with new tires
(32.5" / 27") X 55MPH = 66.2 MPH Actual Speed with new tires
"What can I do to regain the performance?"
Change the differential gears if the truck is equipped with solid axles at a cost of about $400 - $500 per axle.
(New Tire Diameter / Original Tire Diameter) X Original Axle Ratio = Required Axle Ratio
(32.5" / 27") X 3.50 Original Axle Ratio = 4.20 Required Axle Ratio