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Discussion Starter #1
Hey all,

New here and upgrading a 2001 Durango RT. I am at the point of changing over tires after a lift upgrade.

3" Body lift
3" Torsion key suspension lift with accommodating rear shackle lift

I also added helper springs to assist.

I have no intentions of going offroad with this truck. It's a daily driver. Mostly state highway type of stuff. Roads are fairly pot-hole free.

I have the stock rims and 265/70/16 tires on there now. There is so much debate as to what can and cannot fit on these things that I have to ask. I was considering 315/75/16 to add another 2" or so (35 x 12.40 x 16), but there is debate that 35's will cause problems. The torsion keys I got still have well over 1.5" of torque remaining and with the current tires, the shafts are not overly angled at all. In terms of fitment into the wheel well, it seems that the 35" will fit without issue. I may have to mod the fender or bumper slightly, but I planned on changing out the fender to aftermarket in the near future anyways.

So... can 35" tires work? Or is there a better wheel/tire combination that will work to give me 2-3" more lift on the vehicle and fill out the wheel well quite a bit more. There is literally 8-10" of space between the top of the tire and the fenders on both the front and back. It looks silly as all get up now with the smaller tires.

Any suggestions?

Thanks

I can post a picture of the current look now if that would be helpful. Let me know.
 

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My only help will be to assert that 4” of lift and 33s matches perfectly.

Mine:
instagram.com/thatreddodge

It would seem to follow that a 35 and 6” of lift would similarly look good.

You will 100% have to trim the bottom rear corners of the front bumper, but that’s easy.
 

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Hey all,

New here and upgrading a 2001 Durango RT. I am at the point of changing over tires after a lift upgrade.

3" Body lift
3" Torsion key suspension lift with accommodating rear shackle lift

I also added helper springs to assist.

I have no intentions of going offroad with this truck. It's a daily driver. Mostly state highway type of stuff. Roads are fairly pot-hole free.

I have the stock rims and 265/70/16 tires on there now. There is so much debate as to what can and cannot fit on these things that I have to ask. I was considering 315/75/16 to add another 2" or so (35 x 12.40 x 16), but there is debate that 35's will cause problems. The torsion keys I got still have well over 1.5" of torque remaining and with the current tires, the shafts are not overly angled at all. In terms of fitment into the wheel well, it seems that the 35" will fit without issue. I may have to mod the fender or bumper slightly, but I planned on changing out the fender to aftermarket in the near future anyways.

So... can 35" tires work? Or is there a better wheel/tire combination that will work to give me 2-3" more lift on the vehicle and fill out the wheel well quite a bit more. There is literally 8-10" of space between the top of the tire and the fenders on both the front and back. It looks silly as all get up now with the smaller tires.

Any suggestions?

Thanks

I can post a picture of the current look now if that would be helpful. Let me know.

What you may perceive as "Debate" is, that there isn't an easy cut and dry answer. What I mean is this. Although you purchased several components to lift your truck, no two trucks will be lifted to exact same amount using the same components, usually due to age, wear and tear, usage. To drive that point home, you installed a 3 inch body lift. Those blocks go on top of the factory rubber bushings, which can be old, worn, dry rotted, and flattening out. If they are losing their own thickness, you will not gain three inches of lift and this can result in less clearance for larger tires.

Suspension components can also suffer from age, saggy or fatigued springs, etc. So bottom line is, you might not be getting the total amount of ride height you expect, unless you've replaced a bunch of parts while lifting the truck.

To add a bunch of confusion to this, tire size has not been consistent over the years. So lets say you read on every forum that a 35 inch tall tire will fit a specific truck model with "X" amount of lift, but when you go and try it, you discover that your tires are too tall and rub everything. The problem isn't the tires or the lift, the problem is in the way tires were measured. Back in the day, when you bought a 35" tall tire, it was really physically about 34 inches tall. Why they did this? I haven't a clue. But in general no tire using standard measurements were as tall as printed on the sidewalls. So now we have metric tires, and no one really understands what 265 or 315 is in terms of tire diameter. So you plug the numbers into a conversion table, and it spits out that a 315 is equivalent to a 35" tall tire. And that will be a true 35 inches. So a metric 315 is actually a taller tire than say a 35 X 12.5 X R15 and that is going to make a difference in fitment.

As far as causing problems, yes it can. These trucks were never designed to roll on tires greater than about 30 to 31 inches tall. When you go to larger tires, on any truck, the amount of stress on drivetrain, suspension, steering and brakes will increase. Although you do not plan to off road the truck, parts will still wear out quicker, and require replacement sooner, such as wheel bearings, brakes, and even the entire rack…. -as in rack and pinion steering system.

You will also need to swap axle gears, usually to a lower ratio gear, and on a 4x4 you'll be swapping gears in both axles

My suggestion, if you want the biggest tire that will fit, I can't give you a conclusive answer. But I do know that if you have a tire shop who will be doing the work for you, they can often fit tires for you by mounting a tire and seeing if it will fit before you swipe your card.

Ed
 

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Discussion Starter #4
What you may perceive as "Debate" is, that there isn't an easy cut and dry answer. What I mean is this. Although you purchased several components to lift your truck, no two trucks will be lifted to exact same amount using the same components, usually due to age, wear and tear, usage. To drive that point home, you installed a 3 inch body lift. Those blocks go on top of the factory rubber bushings, which can be old, worn, dry rotted, and flattening out. If they are losing their own thickness, you will not gain three inches of lift and this can result in less clearance for larger tires.

Suspension components can also suffer from age, saggy or fatigued springs, etc. So bottom line is, you might not be getting the total amount of ride height you expect, unless you've replaced a bunch of parts while lifting the truck.

To add a bunch of confusion to this, tire size has not been consistent over the years. So lets say you read on every forum that a 35 inch tall tire will fit a specific truck model with "X" amount of lift, but when you go and try it, you discover that your tires are too tall and rub everything. The problem isn't the tires or the lift, the problem is in the way tires were measured. Back in the day, when you bought a 35" tall tire, it was really physically about 34 inches tall. Why they did this? I haven't a clue. But in general no tire using standard measurements were as tall as printed on the sidewalls. So now we have metric tires, and no one really understands what 265 or 315 is in terms of tire diameter. So you plug the numbers into a conversion table, and it spits out that a 315 is equivalent to a 35" tall tire. And that will be a true 35 inches. So a metric 315 is actually a taller tire than say a 35 X 12.5 X R15 and that is going to make a difference in fitment.

As far as causing problems, yes it can. These trucks were never designed to roll on tires greater than about 30 to 31 inches tall. When you go to larger tires, on any truck, the amount of stress on drivetrain, suspension, steering and brakes will increase. Although you do not plan to off road the truck, parts will still wear out quicker, and require replacement sooner, such as wheel bearings, brakes, and even the entire rack…. -as in rack and pinion steering system.

You will also need to swap axle gears, usually to a lower ratio gear, and on a 4x4 you'll be swapping gears in both axles

My suggestion, if you want the biggest tire that will fit, I can't give you a conclusive answer. But I do know that if you have a tire shop who will be doing the work for you, they can often fit tires for you by mounting a tire and seeing if it will fit before you swipe your card.

Ed
Thanks Ed. Nearly everything has been changed in terms of what you listed. Ball joints, brakes, seals, bearings, steering components, etc. The last thing I need to swap out to new is the actual drive shafts for the front. Everything is MOOG or other top quality components. I am not "cheaping" out on this build.
The comment about swapping gears is new. Haven't seen that posted before. Suggestion as to why? Is it simply because of speedo? Or do you have another practical reason. Please explain.

I am aware of the stress change on the parts as well. More or less I am simply asking if anyone has broached 35's with similar setup in terms of torsion keys and body lift. It's not as if there are many lift options for this vehicle outside of doing a SAS, which I am not planning to do. Someone in the world has probably tried this before and I am just looking to get their take on it. Trust me when I say, I am not a noob when it comes to auto mechanics or vehicle restorations/modifications. This will be my first truck lift, but will be my 9th vehicle resto/mod from the ground up.

Thanks
 

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The comment about swapping gears is new. Haven't seen that posted before. Suggestion as to why? Is it simply because of speedo? Or do you have another practical reason. Please explain.
There is definitely a practical reason to swap gears when going to a larger tire. It's a bit difficult to explain without going into a ton of techno-babble, so to dumb this down, your engine produces a certain amount of torque at a given rpm, and basically, the faster an engine spins (rpms) the more torque it should make. A larger tire has a larger circumference which also means that for every revolution, it will travel a greater distance. This would also mean that at any given road speed the engine would be turning at less rpms with a larger tire than a smaller tire. This may sound like a win-win because less engine rpm would also mean less fuel being burned. But it's not that simple because a larger tire takes more torque to turn. Since your engine typically makes less torque at slower rpm, it becomes a lose-lose and it will feel like your engine is lugging, equivalent to driving in a higher gear than necessary. To restore performance, you need to swap to lower ratio gear when bolting on larger tires. To simplify what gears would be necessary for a given size of tire, there are gear ratio- tire size charts all over the internet, such as this one;



A few things to keep in mind when using these types of charts. First, the chart is based on a road speed of 65 mph, and second, the chart doesn't account for over drive transmissions. Most of these charts had been available for many years, even before OD was common, so these charts will be based on the trans in high gear (usually 3rd) or a 1 to 1 trans ratio. Also keep in mind that in the end, a basic rule of thumb is we would want our engine to be running about 2000 rpm at about 65 mph, so when we are using these charts we are more likely to choose a ratio either next to or in the red (ratios for power) so that when OD is factored in we will be within the ballpark for that 2000rpm/65mph window

So, lets start with a factory set up. The typical tire size for a stock Dakota is 30 inches and the typical rear end ratio is 3.55 (Others exist, but this ratio is the most common) When you bisect the 30" tire by 3.55 ratio on the chart, you see the number "2584" This would be what the engine rpm is at 65mph, when running in 3rd gear. (the highest non OD ratio) So lets use this as a base line since it isn't really necessary at this point to compute rpms in OD. We would want to retain that 2584 rpm at 65mph, so looking at the chart and looking at the line for 35 inch tires, the closest we can get to 2584 rpm is 2558 rpm and that would be under the 4.10 ratio. For a bit of extra oomph we could look at the next lower ratio, which would be the 4.27 ratio. However, that ratio isn't available for the Dakota. So the next lower ratio would be 4.56 and that would put your rpms at 65, at 2845 rpm. Now, admittedly that rpm is a bit on the fast side, but remember you still have overdrive and if you wanted to factor OD in we would need to know what transmission is being used. In your case, I believe that will be the Chrysler 45RFE which features a .75:1 OD ratio.

Doing the math using the 4.56 ratio in OD we get;
2845 X .75 = 2134rpm in OD. It's still a bit fast but thats still pretty close to our ballpark figure of 2000rpm/65mph

For the 4.10 ratio we get;
2558 X .75 = 1918rpms in OD, thats almost ideal.

IMO these would be your two best ratio options. The 4.10 will tend to favor economy with the 4.56 favoring power with 35 inch tall tires.

I am aware of the stress change on the parts as well. More or less I am simply asking if anyone has broached 35's with similar setup in terms of torsion keys and body lift. It's not as if there are many lift options for this vehicle outside of doing a SAS, which I am not planning to do. Someone in the world has probably tried this before and I am just looking to get their take on it. Trust me when I say, I am not a noob when it comes to auto mechanics or vehicle restorations/modifications. This will be my first truck lift, but will be my 9th vehicle resto/mod from the ground up.

Thanks
Occasionally a Dakota or Durango pops up on this forum from time to time riding on 35s with similar mods, but based on the durability of the front ends, it really isn't recommended, especially for those who intend to off road their rides. In those situations you'd be much better off going to either a 32 or 33 max tire size. In your case, you aren't off roading the truck, but there will still be stresses that will cause parts to wear out at a quicker rate.

Ed
 

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I love the way mine sits and rides. 3" body lift, 1" blocks in the rear, and slight torsion bar crank up front; fitting 33" tires on 16" wheels with neutral offset (factory is +25)

Tires will rub slightly when turned under compression. Side note: I always measure height for garage clearance, it's 6'10" at top of bike mounts on shell.
 

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The best thing I did along with 4” and 33s?

Easy. That was my rear disc brake conversion and the high $$$ Bilstein shocks. Rides and stops WAY better than a stock durango did, even with the lift and extra rotating mass.

Brakes are off a 98 Grand Cherokee and other than redrilling rotors for 6-lug and opening up the backing plate holes, they bolted on.
 
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