A Better Lift Option for Skinny 35s

[Lion77]

Been mulling over a mild lift and skinny 35s as the ideal for the truck if I lift and do tires.

Im torn between wanting the additional on road handling and wet traction of the new Pirelli XTM ATs that only come in 285/70R17 for now and doing a lift / tires with BFG KO3 35x11.5s.

Option 1 is going to offer much better on-road performance than stock KO3s im on now, which aren't bad onroad and my two gripes with them are the unpredictable brakeaway at lower traction (mainly wet) and they are noisy now with 29k miles. XTMs will fix all that without losing offroad traction. They also save yet another 3lbs per corner and are noticeably quieter. Just a better AT tire for trucks that spend 90% of their time on-road.

Option 2 is doing a lift and skinny 35x11.5s. BFG released their 35x11.5s load C tires about a year ago and they only weigh 60lbs, which isnt much added weight over stock KO3s and lighter than Falkens and some others. Since i have pretty lightweight wheels in ET35 (method 705s), im fine with that as the total rotating mass is still lighter than the stock setup.

Skinny KO3s + 705s = 85.2lbs sprung mass per corner

Stock KO3s + Stock Beadlocks = 92lbs sprung mass per corner.

But im very critical about looking at the whole system, vehicle dynamics, drivetrain loading, gearing losses, inertia changes, possible failure points etc. and overall vehicle dynamics for multiple uses.

1. I want to preserve MOST of the factory rake for utility as I periodically tow and frequently load up the bed.

2. I dont want to have to change out my UCAs or create a bunch of geometry issues so max front lift cant go past 2", with less being more ideal.

3. I want to avoid significantly reducing the SSF (static stability factor) for roll over resistance and higher speed driving safety.

4. I dont want to make the truck handle poorly on-road, but am willing to trade off a little bit of sharpness, braking and turn-in for significant offroad gains.

5. Dont want to kill my gas mileage for cruising on the highway (would be ok losing 1 mpg at most). Wider / heavier tires will do that in a hurry. Dont care too much about city mileage as I dont drive the truck in town regualry so I am willing to accept some loss in fuel econmy for city use which is rare.

6. I want to increase offroad traction in the dirt and at least maintain stock capability in sand / mud.

7. Definitely want to increase clearance if I go with a lift / tires, better get some useful gains for the trade offs!

8. Since im already running a Pro Cal and have a CP-E delta core intercooler on the way (out for powder coating), loosing 2/3 10ths on a quarter mile is acceptable to me becuase its more than offset by the gains from Pro Cal and mitigating heat soak losses.

Most people doing a lift go 2" / 1". But im just not enthralled with that much loss of rake and 2" uses a 32mm spacer, its actually more lift than you need for skinny 35s on mild offset wheels like the 705s.

GOAT knows this, which is why they offer 1.5 / 1 spacer combo specifically for 34s or skinny 35s. I think THIS is the better overall balance.

I want to avoid reducing my SSF as much as possible and preserve as much rake as possible.

A skinny 35 is 21.6mm bigger radius (how much more it sticks up into the wheel well at full compression). The 1.5" spacer is 24mm, so you add just a touch more fender clearance.

This will preserve most of the factory rake, limit SSF loss to the absolutely minimum to run 35s and give you a bit more margin one the geometry / CV wear. Discovering that I dont need to go the full 2" to run 35s has seriously got me eyeing this option!

Minimum Requirements for 35x11.5 KO3s

1. GOAT 1.5 / 1 lift kit

2. BFG 35x11.5 in Load C

3. Forscan + Ride Height Recal

4. Pro Cal now allows you to change Revs per mile, so I can correct the speedo with my Pro Cal

5. APEX Tie rod upgrade.

If Pirelli ever makes the XTM ATs in 35x11.5s id switch out the tires eventually.

Decisions decisions! Both are great options, one enhances on-road / wet traction for minimal cost, the other is a truly ideal off-road focused enhancement that preserves 95% of the stock on-road manners / handling / utility but does cost considerably more.

I still have a while before the stock KO3s are used up, but im heavily leaning towards Option 2 now that I realized I can get away with a slightly more mild lift. And the wider 705s offset negates 50% of the cg loss from the added ride height, so handling losses on-road are very minor for serious off-road capability gains.

One other thing im thinking is a boon for option 2 is cruising long distances. The 35s will ride even smoother. There's even more sidewall and larger diameter just rolls over everything plus added ride height makes for even better visibility yet. All those enhance long distance cruising which I do a LOT of.

And let's be honest, the vanity factor is also heavily in favor of Option 2....not gonna lie!

Most people running skinny 35s dont report any noticeable loss in fuel economy, but those running wider 315s usually see 1-2 mpg loss.

It matters to a degree, but I would be fine with a 1 mpg loss at most, which I think is likely within the window of the skinny 35s.

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[Lion77]

Another benefit is gaining approach, brakeover and departure. A few more degrees would make it just right!

I am really slowly coming over to the "35s offer the optimal balance for the RR" between on-road / utility and very good offroad capability for both high speed and rugged terrain. 35s do also add bottom out cushion. They are air bags essentially, so that also adds to the capability at higher speeds when the terrain is rougher. Thats not really something you need for rally Style prepped tracks or smoother terrain, but for more Baja style on unprepared surfaces / routes it adds real capability.

The Race team did say there was no difference in lap times between 33s ans 35s at finke. They ran both but the 35s added necessary clearance for Baja and they just left them on the truck for consistency since it was already tuned for that.

The race truck also used perch collars to add about 2 inches of ride height up fromt to clear the 315s (they were limited by class rules), but the mild lift + 35s clearly hasn't caused roll over issues in pretty aggressive race use and with over 400lbs more equipment to boot, so my est. on SSF appear to line up with the race truck as my proposed setup is very similar, even the track width is almost identical.

315s on ET45s used on the race truck have nearly identical track width to skinny 35s on ET35 wheels. Im really liking the idea of this combo as the best overall balance between on-road, utility and off-road.

I could do pretty much everything I want including occasional towing.

Even did the final drive calculations. A RR with 34.5" tires still has a 3% lower final drive than an XLT on 31.1" tires and 3.73 rear end, so for towing im still slightly better than an XLT.

Now I would say that I would add a bit of safety margin by not towing more than 5k since towing on the Raptors isnt powertrain related, its stability / braking/ handling. The powertrain will never be as stressed towing max on a Raptor as it would be towing max on an XLT because chassis limits come into play well before powertrain.

I find adding a little more safety margin to tow limit acceptable for the 35x11.5 setup. Its very close to stock with the added wheel offset.

 

[RRaptorscallion0331]

Hey Lion, I’d like to chime in if I may? I got new BFG KO3s on stock wheels for the Raptor rally and they had 285/75/r17s. I think that’s the perfect size however they’re load range E, which for durability is a good thing but I’ve found they are a bit stiff on road. I haven’t noticed any MPG loss nor did I make any major contact during my Fox Jump at the event. No lift, no mods, (removed the front crash bars but could probably get away with them still in place. My point is if BFG does make a 285/75/r17 in load range C, you might like that middle ground until Pirelli makes a decision on other sizes or by some miracle Fox’s 3.2s come to fruition… just my train of thought as I struggled with almost the exact same choice.

 

[Lion77]

Thanks for the input, the 285/70R17s are also a strong consideration. Its always a challenge when modifying street vehicles since they aren't purpose built your always compromising something lol.

Thats one thing I appreciate about side x sides, they are purpose built and while people do modify them, most dont find a need to. Although I will say that even a stock RR is very capable, but like others the one significant gripe is its just a bit shy on clearance.

 

[Pic-N-Stick]

No way I'd go back to the KO3's! At 8600 miles, twice recently I've had them break loose hitting the gas at 30mph on dry, clean pavement! I find myself hitting the 4A button any time I'm considering a hard pull. I also have lost confidence in leaning into a turn in damp or wet conditions. They weren't like this when new. Between that and the road noise they've developed I'm done with them!

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