Fuel and Tires any difference?

[gofast]

So another 72 litres and 576KM. This is running my 235 85 R16 snow tires instead of the 33 12.50 Mickey ATZs. Got a whopping extra 4 km.

Whoo hoo

 

[pathfinder_88]

I am getting about 500-600km's out of 60-70 litres with 265/75r16's.

 

[MARLIN375]

So another 72 litres and 576KM. This is running my 235 85 R16 snow tires instead of the 33 12.50 Mickey ATZs. Got a whopping extra 4 km.

Whoo hoo

Did you take into account that your 33s get you 3-5% further overland than your 235 snowies?

 

[gofast]

So I think I drive like a race car, or used to.

Best ever economy with the 1HZ at 606 km for 72 litres. And I have to get my injectors done!

This works out to just under 12 litres per 100km or just under 24 mpg in the old coin.

But as Marlin says, I ain't getting any where offroad.

Hmmm I'm going to try to drive with more torque and see if I can improve this even more.

Cheers,
john

 

[MARLIN375]

actually what I was getting at was the physical distance you cover with a larger tire. For instance with my 35s, if my odometer says I traveled 100 miles in fact I actually traveled 108 because they are 8% larger in circumference than stock. clear as mud.

so just when i thought my fuel economy got worse, it actually almost stayed the same.

 

[gofast]

True enough, but here's where it gets a little strange. My GPS also shows my speed and when compared to my dash speedometer, the dash unit is consistently out and higher by 6kmh with the 33's. I once did the math before I bought the GPS and thought I could add another 10% based on the up size in tires. So now I'm not sure what the real change is in terms of distance or speed. Who knows how accurate the GPS is for example.

Talking to my buddy who's a master toyota tech and the utimate expert in all things cruiser, (red truck on Whipsaw), he figures I'm hitting a good average for my engine.

 

[MARLIN375]

To get way too techie about it. To get the actual mechanical odometer correction you need to measure the tire radius as it sits on your truck (from the center of the axle to the ground) and compare it to the stock set up. So if you think about it, putting more air in your tires for a road trip would not only decrease your rolling resistance but also put you further down the road for each revolution of your driveline (the later benifit would not show up in your log book but you would get home 5min faster if you always travel at the same RPM). The Speedo is purely mechanical and is only as acurate as Mr T made it, obviously based on an OEM truck. Your GPS on the other hand is very acurate, particularly so if you are on a level road doing a constant speed in open country with 10 or more sats locked. I am not sure if your speed is calculated with 3d inverses or not (it prolly is because it is not a human doing the calcs) if so then it is your actual length of travel (your road surface speed) not a plane dimension (like a map).

We will poll the crew next week and see what their thoughts are.

 

[pathfinder_88]

I run a Garmin unit and it reads within a few km's of my speedo and the 265/75r16's are slighty larger than stock so I think it's pretty accurate.

I should borrow a radar gun one night for those curious...several old ones laying around at work