Larger Tyres and distance travelled

[drgtr]

Larger Tyres and distance travelled

[the evil twin]

How long is a length of string...

Use your GPS to see how far your odometer is out.
It will usually NOT be by the same amount the speedo is in error.
Best way is to travel, say 10k's on the Odo (the further the better) and see how far the GPS says you have gone.

Other option is over a known distance of say 100 K's of road markers

[drgtr]

Thanks Evil Twin.

Is there a formula to calculate differences though?

say from 31 inch to 35 inch rolling diameter and how much it should be out percentage wise?

Also would I be right in my assumption I would be travelling more physically now then what the odometer will show?

[the evil twin]

Thanks Evil Twin.

Is there a formula to calculate differences though?

say from 31 inch to 35 inch rolling diameter and how much it should be out percentage wise?

Also would I be right in my assumption I would be travelling more physically now then what the odometer will show?

The percentage will be 4/31sts... IE 13%
The problem is this... hardly any 35 inch tyre is actually 35 or any 33 actually 33.
Many 33's are often only a tad over 32 and most 35s will actually be around 34ish

I usually work in 5% for each 2 inches change as it is easier and will be awful close... and yes... you will be going further on 35's than your Odo thinks you are.

[MB]

As ET kindly mentions 5% Drgtr is very close I find too on each tyre 2” increase. It also appears for me IIRC that each diff ratio change adds another roughly 5% atop from a trucks OEM plated diffs. 3.9s to 4.1s to 4.3s etc....
Changing from plated stock 4.1s to 4.3s and 35” BFGs tyres seems to be 10% for me according to highway markers as ET also suggested. Best to good GPS check for yourself would no doubt be safest and or drive like me at a grandpa 15% under pace :-) !


Sent from my iPhone using Tapatalk

[drgtr]

Wealth of knowledge as always and appreciated

Thanks guys.

[the evil twin]

Agree with MB... 5% is a golden number when 'guesstimating' what will happen to a Patrol when you change things.
Bigger/smaller tyres - 5% per 2 inches speedo, odo, fuel economy
Diff ratio - 5% per step speedo, odo, fuel economy
Full Roof rack - 5% worse fuel economy
Fully loaded Truck for touring (usually about 300Kg over GVM) - 5%
Full 750 Trailer - 5%, add another 5% for each additional 750Kg

Doesn't always hold true but will be awful close most of the time

[threedogs]

In the tyres specs they should have a distance for the rolling diameter.
Good luck running the 35"s

[drgtr]

Its been great running the 35s lol

Its amazing how well the TD42 on 4.3 diff ratios run it.

So on the Speedo when it shows 90kmh Im really at 104kmh on the GPS and at 95 Kms Im really at 110kmh

So its 15 percent difference.




Low speed I can feel the mud chunky treads
Higher speed Its noisier but still smoothish.
Slight driveshaft vibration if I dont load the clutch starting off on low rpm sometimes.

Originally at 110 kmh I was at 2670 rpm with the 275 75 16 (5th Gear)
Now at 110 kmh Im sitting on 2180 rpm with 315 75 16 (5th Gear)

Im using less fuel already. I dont even get out of 4th gear in the suburbs.
I dont even need to rev past 2000 rpm as it is still comfortably in the torque band.


Im very happy overall.



So if the odometer shows I have done 100kms distance do I add the difference of 15 percent on top for the distance too? to get the real distance travelled?

[MB]

I do get confused easily Drgtr mate and will have to defer to ET here. +\- tyres/diffs etc....
I do know that a BFG Km2 muddie varies shiploads from fresh to sand tyre worthy :-)


Sent from my iPhone using Tapatalk

[drgtr]

I do get confused easily Drgtr mate and will have to defer to ET here. +\- tyres/diffs etc....
I do know that a BFG Km2 muddie varies shiploads from fresh to sand tyre worthy :-)


Sent from my iPhone using Tapatalk


lol mate im no expert either. Im far from probably even understanding :D

Appreciate your advice and no doubt you know more than me.
Im new to this

the wheels are negative 22 offset.
I been trawling forums and internet trying to learn

really it started from why I was revving quite high on 5th gear at 110kmh. Then realising my car has the 3litre 4.3 diffs rather than the 3.9 diffs.
was a blessing in disguise.

the 35s were given to me so I couldnt resist.

[drgtr]

Update:

So before 35s and Roof Rack. I was averaging 16.4L/100km.

Now with 35s calculated twice. Same driving pattern. 15.8L/100km.

I love on the highway now Im around 2100rpm at 106kmh too.

Gotta Love Turbo Diesel 6 Cylinders.

[MB]

Update super appreciated for my learning too mate! So...many variables we all experience in this great land. Flat open hauling to hills, to humid snow cold air intakes, to humid tropics, to 2.8/3.0/4.2D ~ 4.5/4.8P & Conversions x tyres/ratios = 15.8L/hundgy on your beast loaded sounds pretty damn good to my nuffy experience :-) !


Sent from my iPhone using Tapatalk

[drgtr]

Thanks MB.
It made sense to get some conclusion.
Im very happy to say the least.

The only downside to the 35 was it created more vibrations around 1200 rpm or less especially on 2nd gear.
No doubt the extra unsprung weight has moved the Harmonics/vibration around.

The exhaust muffler was fixed and mounted tighter as that created a very fast vibration sound brrrrrrr when it touched the towbar underneath the car.

The second vibration area was coming from the front . Similarly very fast brrrrrrrrrr vibration. was the Coil Springs because the rubber tops were shagged.
Changed that today too and now nice and quiet.

If a noise is there and its not normal but not detrimental. It plays on my OCD. I have to get rid of it and im happy I found both! :D


If a noise is there and its a nissan patrol Td42ti thing like the 1st and 2nd Gear chatter (gear roll over noise) on low rpm. I can live with it haha.


Overall
a Td42Ti on 35 inch with 4.3 Ratio is a very pleasant car to drive

Hopefully this helps other people who read this and wish to go down this path.

[MB]

....Done.....:-)
This post will be fried in T minus 5 minutes brother ;-)


Sent from my iPhone using Tapatalk