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Offline Dlc2cg5

Speedometer
« on: August 31, 2016, 04:45:19 PM »
I just put a new set of tires on my Zforce and went from 26" tires to 28" in front and 30" in rear.  Now besides raising it up about 3" my speedometer is off a lot.  I think it might be as much as 10-13 miles/hr. Off.  Anyway to reset it?

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Offline NMKawierider

Re: Speedometer
« Reply #1 on: August 31, 2016, 04:55:41 PM »
I just put a new set of tires on my Zforce and went from 26" tires to 28" in front and 30" in rear.  Now besides raising it up about 3" my speedometer is off a lot.  I think it might be as much as 10-13 miles/hr. Off.  Anyway to reset it?
You can not put different diameter tires on a 4WD as they rotate are different speeds. You will destroy usually the differential...and that's a hair over a grand. You have to have either 28s all the way around or 30s all the way around. Do not put that in 4WD with the 28s and 30s. You will be very unhappy with yourself.
« Last Edit: August 31, 2016, 08:07:47 PM by NMKawierider »
2015 Z Force 800 (53") EPS -
Custom Air Intakes | Custom Exhaust Mod | SuperATV Harness | Custom Fenders | Custom Skid/Rock Sliders | 27" GBC Grim Reapers | Seizmik Mirrors |Конструктор (Rodin's) Doors | Dr Pulley Sliders | 1.5" Wheel Spacers | BENZ Silencer (as needed) | SATV Flip Windshield W\ Rear Shield | Dual Light Bars | Diamond Plate Storage | 9.7" GPS | Bandit Springs Rear & Gen-3 Shocks Front

My Videos On YouTube

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Offline Jogon30

Re: Speedometer
« Reply #2 on: August 31, 2016, 05:28:51 PM »
I agree with nmkawi just google it and you will see that what you did is a big no no the same all the way around be carefull or If you have it under warranty save your old stuff just in case you have to take it in for service lol !
« Last Edit: August 31, 2016, 06:20:56 PM by Jogon30 »

Re: Speedometer
« Reply #3 on: August 31, 2016, 07:31:03 PM »
Yes, definitely, same size on both ends.

As far as I know, no way to fix the speedo.
2015 ZForce 800EX EPS
Two Bros. slip-on
Snorkels
Half windshield
30" Monster mayhems on STI HD2s
2" lift
Secondary clocked to C4
1mm Primary Shim 3.25:1 Lowest Ratio
More to come

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Offline Dlc2cg5

Re: Speedometer
« Reply #4 on: August 31, 2016, 09:06:26 PM »
it came with 14" wheels and that is still the case only now I have taller side walls which make it have more ground clearance.

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Offline Jogon30

Re: Speedometer
« Reply #5 on: August 31, 2016, 11:23:09 PM »
What's wrong with this picture ? Now let's pretend you hit the 4x4 button . And even if there was no damage you would never get the speedo to work depending on we're the speed sensor is, if it was in the rear, the tire rotation would be greater and it would measure less speed if it was in the front smaller tires faster rotation more speed . Unless I'm wrong but I think I'm I the right path here lol? Guys right ?
« Last Edit: August 31, 2016, 11:29:55 PM by Jogon30 »

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Offline NMKawierider

Re: Speedometer
« Reply #6 on: August 31, 2016, 11:50:44 PM »
Oh that's right thinking. On thee the speed sensor is on the front output shaft so no matter how fast the output shaft goes, and its tied in with the rear and engine all the time, that's what the sensor will pickup. Soon as he hits 4WD and locks the fronts to the backs, in less then 15 feet the front ring and pinion will load-bind and do what ever it takes to.. "part company". That usually means the case breaks under the load. In soft dirt the tires might slide but not on hard pack or pavement.
« Last Edit: August 31, 2016, 11:52:58 PM by NMKawierider »
2015 Z Force 800 (53") EPS -
Custom Air Intakes | Custom Exhaust Mod | SuperATV Harness | Custom Fenders | Custom Skid/Rock Sliders | 27" GBC Grim Reapers | Seizmik Mirrors |Конструктор (Rodin's) Doors | Dr Pulley Sliders | 1.5" Wheel Spacers | BENZ Silencer (as needed) | SATV Flip Windshield W\ Rear Shield | Dual Light Bars | Diamond Plate Storage | 9.7" GPS | Bandit Springs Rear & Gen-3 Shocks Front

My Videos On YouTube

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Offline chuddly

Re: Speedometer
« Reply #7 on: September 01, 2016, 08:50:21 AM »
Lets try to explain this out for our OP. 

For this math we will be assuming that a 28" tire is actually 28" exactly and so on.
With a 28" tire the circumference (distance around the tread) is 88"
with a 30" tire the circumference is 94"

So with the 28" tire on the front one rotation of the tire travels 88" and with the 30" tire it travels 94".  Of course your front axle and your rear axle can not travel different distances because the front and rear are fixed together by the chassis and suspension so what happens is either the tires slip on the ground (best case scenario) or and much more likely one of your differentials breaks (usually the front one) and you get to spend $1,000 and still replace the tires.  While some may thing that "OK so my front tire will just travel less distance" it doesnt work that way.  The tires have to move at the same speed across the ground so in doing so there will be constant binding between the front and rear.

You had referenced the wheels were 14" and yes that is true.  but the tires are the "final drive gear multiplier" in your drive train.  Wheel size could be 12" on the front and 14" on the rear and the machine wont care in the least as long as the OVERALL tire HEIGHT is the same.  See the picture below on plus sizing wheels


Lets do a little bit of basics on tires while we are all here just to make sure we all understand what those numbers mean.  First we will focus on the our UTV/ATV tire sizing standards.  For this we will use the tire size 26x9x14 tire.  26" is the over all height of the tire. 9" is the width of the tread of the tire. and 14" is the wheel diameter that that tire fits (this wheel diameter does not include the lip of the wheel).  If you want a bigger (taller) tire you could go with a 27x9x14 and the tire would net you 1/2"  more ground clearance (only 1/2" because you gain 1" in diameter and only 1/2 of that is below the center line of the axle.  Thus the other 1/2 is at the top of the tire and not actually helping with clearance).  But to do that and not snap important drive pieces you would have to do all 4 tires at that size.  If you just wanted a wider tire you could do a 26x11x14 and you would gain 2" of width (what  most do on the rear) this is ok to just do on the rear as you do not change the overall height/gear ratio of the tire.  If you wanted bigger wheels with less sidewall you could go with 26x9x15 and your wheel would be one inch larger but the overall tire size would be exactly the same so no issues there.

Now CAR TIRE sizes are much different.  We will work with 225/75/R15 as a tire size.  225 is the width of the tread in MM (notice the width is in a different place in the number sequence).  75 is the sidewall height and it is a percentage of the width.  So in this case it is 75% of 225 MM which comes out to 168.75 MM.  The R means it a radial.  the 15 is still the wheel diameter in inches.  I know that can be confusing but in the ATV/UTV world we dont have to deal with that LOL.

I hope this helped some and explains WHY its a HORRIBLE idea to mix and match overall tire heights and the damage it can cause.
« Last Edit: September 01, 2016, 10:45:12 AM by chuddly »
I can imagine a world completely at peace.  A world where there are no weapons, no war, and no violence at all.  And I can imagine us taking over that world because they would never expect it.

Re: Speedometer
« Reply #8 on: September 01, 2016, 08:28:03 PM »
That's a good explanation.
2015 ZForce 800EX EPS
Two Bros. slip-on
Snorkels
Half windshield
30" Monster mayhems on STI HD2s
2" lift
Secondary clocked to C4
1mm Primary Shim 3.25:1 Lowest Ratio
More to come

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Offline Wheels

Re: Speedometer
« Reply #9 on: September 01, 2016, 10:54:24 PM »
Hot Rod Z8 , just pull the front axles and go for it.
30 rear and 24-25 front would look great. Chop the roof!
If it has Pistons or Tits you will encounter problems.

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Offline Dlc2cg5

Re: Speedometer
« Reply #10 on: September 02, 2016, 12:48:30 PM »
You guys have given this some real though and I will admit much more than I did.  I agree with the idea of using the same size.  I my have taken the wrong advice (my tire guy) but I am going to try to live with my mistake.  I came up with 4wheel drive pickups decades ago and reguired you to be very careful about leaving the front engaged on dry, hard surfaces.  So being old school I still use 4x4 very sparingly and hope I can get by for this set of tires.
« Last Edit: September 02, 2016, 12:50:17 PM by Dlc2cg5 »

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Offline NMKawierider

Re: Speedometer
« Reply #11 on: September 02, 2016, 01:04:27 PM »
Ok then. Also be aware you no longer have on-the-fly 4wd as the two are spinning at different rates. Doing so will probably break the coupler or actuator on engagement so stop every time you put it into 4wd. Alpha Sports sells complete front differentials for just over a thousand. Good luck. :)

2015 Z Force 800 (53") EPS -
Custom Air Intakes | Custom Exhaust Mod | SuperATV Harness | Custom Fenders | Custom Skid/Rock Sliders | 27" GBC Grim Reapers | Seizmik Mirrors |Конструктор (Rodin's) Doors | Dr Pulley Sliders | 1.5" Wheel Spacers | BENZ Silencer (as needed) | SATV Flip Windshield W\ Rear Shield | Dual Light Bars | Diamond Plate Storage | 9.7" GPS | Bandit Springs Rear & Gen-3 Shocks Front

My Videos On YouTube

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Offline chuddly

Re: Speedometer
« Reply #12 on: September 02, 2016, 01:17:23 PM »
yeah...its cheaper to get 2 new tires now than a new diff later.  But its your machine and your wallet so do as you like.
I can imagine a world completely at peace.  A world where there are no weapons, no war, and no violence at all.  And I can imagine us taking over that world because they would never expect it.

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Offline chuddly

Re: Speedometer
« Reply #13 on: September 02, 2016, 01:18:10 PM »
Also....whoever your "tire guy" is....dont go near him again ....ever.  He doesnt know anything about tires LOL
I can imagine a world completely at peace.  A world where there are no weapons, no war, and no violence at all.  And I can imagine us taking over that world because they would never expect it.

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Offline Dlc2cg5

Re: Speedometer
« Reply #14 on: September 05, 2016, 09:57:28 AM »
Just to let you guys know how my tire mistake is going by now.  I talked to "my tire guy" and he agreed that putting different sized diameter tires on a 4x4 is a no no.  He said that he was sorry for the mistake and will do what ever it takes to make it right.  So I will have a new pair of 30" Mongrels on Tuesday.  He also said he remembered I was going on a ride yesterday (Sunday) and if I needed the tires switched around just for that ride he would do it.  I didn't take him up on that because I didn't think I would need 4 wheel drive on the ride.  Well as it was I did need 4wheel drive as I was second from the last unit on part of the ride and the last guy broke down.  So I not only had to use 4 wheel drive to tow him through the creek twice but up some step, rocky logging trails about 3 miles to get him out and on the road. 
So after all that, yes I am getting the same size tires on my machine.  Plus everyone was very impressed with my zforce800 being able to tow that broken Ranger out of the woods.  Cf Moto is a good machine.