iForce Max MPG With 33x12.5x17 Tires & New Wheels

Riley_monthule · 2025-07-13T23:01:57+00:00

REASON: The rear end of my 4G wasn't as high as I would like it and didn't feel properly supported with my new BYND camper Even with the Peak 2.5" spacer so I bought a set of Dobinsons springs for the rear to solve both these problems. NOTES: When buying Dobinsons you almost always want to spec the spring one below what it says on the website. I've installed their springs on dozens of vehicles and their website recommendation is never correct. For example they have the C59-821V spring for my truck which states it adds 2.25" of lift at 440-660lbs of added weight in the bed. I have about 500lbs of added weight fully loaded with the new camper and I want 2.25" of lift so this spring should be perfect but it would've been way too stiff. I ended up going with the C59-819V spring which states it adds 2.25" of lift at 175- 330lb Load and 1.25" at 440-660lb Load, Again this is wrong. With 500lbs of weight in the rear this spring gave me almost exactly 2" of lift and feels perfect my for setup. Still flexes great and the ride is stiffer but not too stiff. This has been true for every vehicle I've ever used their springs on so just watch out for that and take my weight as consideration for what you should use. We've corrected this on more than one of our customers vehicles at my shop where they buy the spring it says they should on their site and it's like a pogo stick in the back. Also make sure you have accurate weights. We have scales at my shop so I knew exactly how much extra weight I needed to support. It's better to just get your vehicle weight if you can rather than guessing. If you're installing these I would highly consider upgraded adjustable shocks as well. If you just increase the effective spring rate with out increasing damping the rear end will feel bouncy. CONCLUSION: With the proper spec these springs achieved exactly the lift and support in the rear I was looking for. They're progressive so they handle various loads great and I personally love the classic Dobinsons teal color. If you look at the pictures you'll see my truck now has some decent rake with the current no lift in the front. I'm going to adjust my front coilovers to level the truck which should give it the perfect stance and just about 2" of lift all around. I also included a side by side with the stock springs. One with and without the peak suspension 2.5 rear spacer. you can see with the spacer they're almost exactly the same height and without it the stock spring is much smaller. I would not recommend a spacer on the rear spring as the Dobsinsons is a proper upgraded progressive spring over the factory spring and the spacers are basically the same price as new springs especially if you're having a shop install them. INSTALLATION: Time = 1Hr if you know what you're doing* 1. With your truck on the ground undo your sway bar end links. It's easier to access the end of the link that's connected to the sway bar rather than the frame. 2. Now undo the top of your shocks with a 19mm and a wrench holding the center of the shock from spinning. A ratcheting wrench makes this much easier. 3. Undo the upper link of your panhard bar. This will allow the axle to droop low enough to get the new taller springs in. 4. Undo the brake line brackets on the body on each side of the axle and the e locker wire bracket on the top of the diff. This will allow the axle to droop without straining any of the lines/wires 5. Slowly lift the vehicle until the rear tires are off the ground while watching all the lines to make sure none of them are starting to be strained. if any of the lines between the axle and body/frame tighten up put the truck back down and loosen the required brackets to provide slack. this is much easier with a lift and might be required depending on your spring. These new Tacos have a ridiculous amount of droop when not limited by any components. I'm not sure if a jack will be able to get the vehicle high enough and it's hard to use spring compressors for installation on this vehicle but probably possible with patience. always make sure to block the front wheels if you're using a jack. 6. The rear springs might fall out at this point so watch out for that. If they haven't you should be able to just pull them out at this point. Again make sure the truck is properly supported before getting under it. If it falls especially without springs in it you probably won't make it to tell the story. 7. Move the lower & upper rubber spring vibration dampeners over to the new springs. The lower ones are glued on so just take care not to rip them when pulling them off. There's little slots for zip ties on the lower ones so you can reattach them to a new spring. The upper ones just place right on top of the spring. 8. Position the new springs making sure the bottom lines up with the lower perch correctly. You might have to clock/turn them a little to achieve this. When turning them you'll notice they fit much better and stand straight up in a certain orientation. The truck will sit lopsided if this is not done correctly. 9. Slowly lower the truck making sure the spring position stays correct. 10. Lower the truck the rest of the way down making sure the top of the shocks go back into their holes. This is made easier with a friend or if you're by yourself like I was you can put a long socket through the shock mounting hole and line it up to be on top of the shock. this will guide the top of the shock into the hole when lowering the truck. 11. Redo everything you took apart and you're done! If you go with 2" or higher a panhard correction mount or adjustable panahard bar is recommended for proper suspension travel. If you don't do this you'll notice the rear of the truck moving back and forth, left and right when going through it's travel. Let me know what you guys think and if you're considering Dobinsons springs! I went with these over the competitors because of the range of weight options and the color options but I'm curious if anyone is enjoying another brand. Thanks for reading and let me know if you have any questions!

rustytaco

Administrator

Staff member

Feb 19, 2025

#1

Stop and go with some coasting on my new setup. Arroyo RTs (33x12.5) and Lock Off-Road Combat wheels. Smaller wheel, but larger tire. Definitely added some weight to each corner. This was paired with a 2.25" lift kit from Peak and no air dam. Not bad at all on winter blend gas and single digit weather (I'm in Illinois). Seems like I'm doing roughly 18-21 mpg depending on the situation. Could get more consistently above 20 if it was warmer, better gas, etc.