Yup thats right... I lost 2 miles to the gallon... now I average 14, which still isnt that bad but no way am I going to go to 315's. I will take the loss cuz the tires look kick ***.

 

What gear ratio do you have. I'm going with the 315/75 MTR's in the next couple of weeks but i'll be upping my gears to 4.56 soon there after. One question though. Are you finding that the tires are difficult to balance or keep balanced?

 

I have 3.55's in it. It is so expensive to the front and rear gears and I have to travle 15 miles 1 one on the highway to work. 4.56's will certainly kill the mileage. I have had the tires on now for three thousand miles nad I don't have any shakes what so ever, so in short terms- no problems with balancing. If you dont worry about mileage- definetly do the gears and put the tires on... it should look really nice- and have torque up the ying yang!

T

 

Are you factoring in the % that your odometer and speedo are off now? Or have you already fixed that with a new VSS gear?

If you haven't changed the speedo gear, and are using the mileage shown on the odometer, your recording less miles then you actually have traveled. You could be off by at least 10% now. For example, add 10% to the miles that show on the odometer and that's how many miles you have actually traveled.

 

I have 3.55's in it. It is so expensive to the front and rear gears and I have to travle 15 miles 1 one on the highway to work. 4.56's will certainly kill the mileage. I have had the tires on now for three thousand miles nad I don't have any shakes what so ever, so in short terms- no problems with balancing. If you dont worry about mileage- definetly do the gears and put the tires on... it should look really nice- and have torque up the ying yang!

T

 

I mean the speedo gear. It's a twelve dollar plastic part that calibrates the speedo and odometer. Since you have a 98, it should have one.

So, if you have not changed it, when your speedo shows 60
mph, you are actally going like 66 mph if you were to be radar gunned. This means that your odometer is off the same amount.

So for every 10 mile posts you pass on the freeway, your odometer will say you only went past 9. You basically lose one mile for every 10 you actually travel. So, if your odometer says you went 300 miles, you would have to add 30 miles to that so you really traveld 330 miles. That's what you would use to compute your true mpg's.

This is all based on the assumption that you are 10% off. My rig, with the 265/75/16's were 5% off.

 

tlapan93 what kind of tire do u have the ones on your truck dont look like wrangler mt/r

 

I guess I will need to do a longer trip than to and from work... this trip is 30 miles round trip using my mustang and the truck before the bigger tires were on. It still reads the same witht he bigger tires- 30 miles. I am going to have it radared this weekend... will let you know. Thanks for the input.

Stevens- I just looked at your pic- then went outside because the mt/r are what I bought from tirerack. They say goddyear mt... no R- what does that mean?

 

tlapan93,

You lost more than 2mpg with 33"+ tires with 3.55 gears. Your engine is working much lower in the power band, and is not as efficient. Your load and towing capacity have gone way down also. Notice what your transmission is doing when going 70mph on the highway up a hill. You may also want to consider driving with the "overdrive off" to ease the load on the engine. The bigger tires do look nice.

 

The tires you have are MT's and not the "new MTR's".....If you indeed ordered the MTR's and it shows that on your receipt, I'd say you are entitled to some new tires....


Pics of my 315/75/16 GoodYear MTR's at www.picturetrail.com/4x4

 

Guys, what should I do to fix this bigger tire delima? All this shifting uphill on the highway is killing it... Is there a performance upgrade that will help this out that isn't a ton of $$$. Thanks in advance. T

 

when I called Tirerack and spoke with a rep I asked for an aggressive tire that would work in the snow as well as give a decent ride. They suggested both, and I specified the more aggressive tire. It appears I didnt receive the wrong tire- I just assumed I was getting the MT/R- In any case I love these tires and I only paid 147 per tire so I wont bitch...

 

when I called Tirerack and spoke with a rep I asked for an aggressive tire that would work in the snow as well as give a decent ride. They suggested both, and I specified the more aggressive tire. It appears I didnt receive the wrong tire- I just assumed I was getting the MT/R- In any case I love these tires and I only paid 147 per tire so I wont bitch...

 

This will correct the shift points, correct the speedo/odometer, and add a little performance...i got one for my truck and it has helped...Glad to hear you got what you paid for on the tires and that tirerack didn't pull the old bait and switch on ya

 

I wouldn't bet changing gears to 4.56 will lower gas mileage further if you already had 35" tires. Mainly because when you have tires like that, your RPMs will be much higher because your engine is working "out of its powerband". Basically- its having to try harder. Even a few hundered RPMs all the time can make a big difference. Although usually 4.56 gears would lower mileage on a stock truck- on one with 35 tires who is already going several hundered RPMs over normal, those gears will lower it back down (esp. in overdrive, where mine right now is about 2100 RPM overdrive!!!), and the truck will see more normal RPM numbers, which should bring back the gas mileage some, not take it farther away.

GET THE GEARS!!!!!!!!!!!!!!!!!!!!!!!