? Steps to Reduce On Power Tire Spin?

I would consider myself a 1/2 way decent car builder/ tuner…however… I still have plenty more to learn from you fine folks that are far better than I. My learning is the reason for this post as I have a question for you folks. This topic is about correcting on power tire spin… basically spinning the tires when accelerating (on the gas pedal). I FULLY UNDERSTAND that throttle control is the MAIN thing one can do in order to prevent tire spin & I have/ utilize throttle control at all times. I also run w/o any assists.

I’ve been successful at correcting on power tire spin by adjusting the ACCEL Differential up or down. For a really stubborn car I will also try to adjust out on power tire spin by lowering rear spring rate, raising the rear ride height, raising the front bump, & lowering the rear bump.

What is your guy’s steps in correcting on power tire spin? Also, does changing the transmission on a RWD help… basically switching from stock to sport or race?

Thanks in advance for any & all guidance!

Two easy fixes I often do. First the build, make the rear tires wider. There is no substitute for rubber on the road. Second, a little negative toe. I’ll use up to -.3.

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Thanks for the response FOOT. When I build my cars I always go with the widest tires possible & my tunes always have some level of negative toe. However, I still have cars that I have to work to get the on power tire spin under control.

For example; I have built the 2002 Corvette to be in S-Class. I already have this car built for A-Class but wanted to utilize it in the S-Class lobbies as well. The car is great on the track EXCEPT for being really, really sensitive to throttle input. I’ll give details of the build & tune below (well, as much as I can remember since I don’t have the game on right now):

2002 Corvette - S800 PI

Engine Upgrades are all RACE except for the ignition is sport (I think)

Brakes, Springs, Sway Bars, Roll Cage, Weight are all RACE

Clutch & Transmission is STOCK… can’t remember the driveline choice… Differential is RACE

RACE Tire Compound & widest tire selection

Front/ Rear Forza aero


Weight = 2695 lbs

Front weight/ Distribution = 54%

Front tire = 295

Rear Tire - 345

Tune Info:

Tire PSI = 29 PSI front & rear

Camber = 2.5 front & 2.0 rear

Toe = 0.0 front & -0.2 rear

Caster = 5.4

Sway Bar = 15.8 front & 18.5 rear

Springs = 553.6 front & 322 rear

Rebound = 6.8 front & 5.8 rear

Bump = 5.5 front & 3.5 rear

Aero = 100 front & 200 rear

Differential = Accel @ 60% but I’ve tried a bunch of different %'s from 35% to 80%
Decel @ 35%

Foot or anyone for that matter… do you folks see anything within my build or tune that may help correct tire spin?

ACTUAL - In addition, to what FOOT described above, I have been sometimes (depends on car/class/track combo) successful with balancing the front-to-rear ratio of the aero settings. For example, I had a muscle car weeks back where I actually came up with a 2nd build with add’l grip and less power, yet, the one with the higher power at the same track did not show signs of wheel spin (or at least, I did not notice during my test runs), whereas the less HP build did…very weird. Thus, I tweaked the aero (front & rear) and the Diff (slightly) to minimize such, yet, still shows some of it depending on my line/driving at that particular turn.


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I hear you! I had a centrifugal supercharger on the 2002 Vette but I took it off & just utilized the normal aspiration parts for increased HP. Taking off the centrifugal supercharger made the weight distro go from 56% to 54%. This all helped reduce the tire spin but it’s still a problem.

Ok, I used your build and tune but made the following changes:
Psi 28/27.5
Rear toe -.3
Rear rebound 7.8
Accel 33%
This car is going to require throttle control no matter what, but I was able to get around Catalunya GP in 1:53.0 without lighting up the tires. Not going to compete with the X-Bow or Ferrari 512, but not bad.
Keep in mind that the vast majority of people in S class lobbies are probably running TCS. I never see too much tire smoke when I venture in there.

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Ok, you want some “why” behind the “how”.
PSI, slightly lower pressure = slightly larger contact patch.
Toe-in, when the tires are slightly toed-in they resist turning giving more stability to that end of the car. Toe-out increase the cars willingness to turn. And despite some claims otherwise, there is no effect on speed due to scrub.
Increase rear rebound, keeps the car “squatted” longer instead of balancing out so fast.
Diff. Accel, I started out at 10% and could feel power being wasted with unloaded (inside) tire wheel spin. Kept increasing by 3% increments until it was putting the power down without breaking the loaded (outside) tire loose.

I can explain every variable and why I adjust it, but I suck at typing. That’s why my posts are usually brief.


Thanks Foot! The explanation was on point & I understand what you’re saying.

I’d be running slightly softer springs and much lower sway bar and softer bump. Lowering the tyre pressures a little can also help keep the rears in the grip range when you’re tramping it. The race cage may also be working against you by being too rigid in getting the power to the road. Instead of some of the stress being absorbed by chassis flex it goes straight through to the contact patch. Another obvious option is to drop in the race box and set your exit ratio(s) a little longer. Funnily enough the diff will probably only help you much if you use it to nerf the power down, but that will affect you adversely elsewhere on the track . The sweet spot on most RWDs seems to be in the 65-75% range. If the car is squatting to one side at the rear and hooking you around, raising the relative rear bump can also help with that. You can do a lot with minor ARB adjustments. End of suggestions dump. :wink:

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NOTICE: I’m asking questions in order to learn & become a better tuner.

What does the changes to the rear rebound & toe do in order to fix the tire spin? Basically… how does it work? I also thought that the toe settings ONLY effected the cars ability to turn in… going into the corner… corner entry?

What are you considering to be “soft(er)” springs, bump, & sway bars? I ask because I thought that I was already running a pretty soft setup? Again, asking questions to learn… not to question y’alls ability! I’m the student hear!

I’m still stuck with FM4 knowledge, but this applies to everything including real life… Short gears can help minimize wheelspin.

Lets say I have a “short” 3rd gear set to top out at 100MPH. If I’m doing 80MPH and I spin the tires, the tires cannot exceed that 100MPH because of the gearing. While I am spinning my tires, my drive tires are only going 20MPH past the limit of grip.

Now, lets say I make 3rd gear “long” and it tops out at 130MPH. Again, I’m doing 80MPH and I spin the tires, but now they’re gonna spin up to 130MPH, which is 50MPH past the limit of grip.

Basically, the longer your gearing is the faster your tires can spin when you exceed the limit of grip. You want to limit that difference in speed that I talked about (what’s bolded above); less speed difference = less wheelspin.

If you build a car with all 6 gears within 10MPH of each other and you mash the gas, you will actually get very little (if any) wheelspin, because the tires cannot spin more than 10MPH past the limit of grip. The problem with this setup is you’ll be shifting too often and you won’t have enough gears to go faster than 60MPH. You have to find a middle ground between long and short gears, but keep in mind what I’ve said.

Hopefully this all made sense, I’m not the best with explanations. : /


Dude… great explanation! I’ll be back over to FM4 soon… gonna start splitting some time between FM6 & FM4.

I actually haven’t played FM4 in 2 or 3 months. Heck, I barely even post on the forums anymore. I’m sure the ol’ gang would be glad to have you around though. : )

You can also minimize wheelspin with long gears BTW. But more than anything it comes down to throttle control; a great tune can’t make up for poor skills, but great skills can make up for a poor tune.

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Not shared since I am completely out of tune room, let me open up 1-2 tunes and share it out.


I would probably start out with with the springs closer to the actual weight distribution with 460-490 on the front. A full unit less bump, and around half each on the ARBs. I haven’t played with the car at all but the front looks a bit stiff and over-planted to me whcih means the rear end is going to be doing a lot of work (unecessary) coming out of turns. Softening up the front a bit will get it working harder and give you back some of your rear stability and grip. Also, with the race cage you can drop ARBs a lot lower than you might think, helping turn-in and making the car more compliant and less reactive to kerbs.

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I threw together a rough build shared as S800. Not something you would let your mother drive but that’s S class I guess. The car is way overpowered for its chassis and grip. From memory tyres are 27.5 front and rear, camber -1.6/-1.5, arbs 10/5, springs 495/435, ride height 4/4, diff 65/26, brakes 58/160. Race transmission set to 5 gears. Stock cage worked best. Didn’t touch caster or toe. You need to lift the rear rebound a little to get decent track out.

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Thanks Mick!!! I took yours & gtFoot’s guidance & spent well over an hour playing around… tweaking the tune. It definitely got better but I noticed the best change was dropping HP & adding the Race Trans. I’m going to download your tune & run it on the same tracks I tested on! Thanks again!!!

I am also very much a student compared to the majority of you tuners and at the risk of being being told I am wrong and my opinions on “how you drive” or “style” coming into play is “just an excuse for not being any good” again, I would like to throw out my 2 cents.

When I looked at your initial setup, Outkast, the rear camber seemed very high to me. When a car accelerates, the rear will drop. The degree it falls depends on springs, rebound, etc. When this happens, the wheels are going to increase the negative camber at least a little bit no matter what. When this happens, the increase in negative camber will put alot more weight on the inside of the tire and less on the outside, reducing the actual contact patch of the tire which in turn reduces the grip you get.

The toe thing I will say for sure that I don’t understand how that would help grip on acceleration. This turns the wheel/tire from being staights to either fighting itself inward or outward, depending on which way you set it. Seems like the straighter the wheel or tire is to going forward, not fighting itself would help acceleration more. Again, I am also trying to learn!! Please keep that in mind.

I have built and tuned many, many drag cars in 6. I’m not a fan of the public wreck fests and I just plain enjoy drag racing so that is what I do quite a bit. There have been a few times where I have actually gone to a SLIGHT positive camber in the rear, maybe a couple tenths or so, so that when my car launches and the rear drops, the tire are flat against the road, giving a full contact patch instead of just the inside edge of the tire.

As far as tuning camber and toe for handling in and out of corners and fun on track tuning, the definitely needs to be a middle ground found. As I said, I am just trying to learn what I can and acknowledge most of you guys have much more experience with the serious tuning than I do but I do understand physics and have a pretty good knowledge of how cars work on the real world. How that translates to Forza is certainly a learning experience.

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