Does added negative toe (in) increase traction at rear?

[kb135]

As the title says, does adding more toe in at the rear (say 1mm to 2.5mm per side) increase your traction on take-off? Reason I ask is, just two weeks ago when I had my 18"MPSS (225/255) and 1mm toe in rear, I could spin wheels in 1st and 2nd gear while rolling at 40km/h. Now with my 19"MPSS and 2.5mm toe in (same 225/255 widths) I am finding it very difficult to even spin in 1st while rolling. (Obvious factors have been checked, DTC completely off, boosting healthy etc.)
Any ideas?

[DRedman45]

yes it does, but added weight of 19's also makes a huge difference

[kb135]

Hmm. Did some checking and turns out both the 261M 18"and V710 19" wheels weigh the same? Has my research failed me?

Will do my own weighing this weekend.

[RimasRS]

Originally Posted by kb135

Hmm. Did some checking and turns out both the 261M 18"and V710 19" wheels weigh the same? Has my research failed me?

Will do my own weighing this weekend.

Interesting to know difference. Please post results.

[IGoFast1589]

When you take off the rear end of the car will squat down and your dynamic toe settings will change from what they are when static.

[kb135]

Originally Posted by IGoFast1589

When you take off the rear end of the car will squat down and your dynamic toe settings will change from what they are when static.

Ah yes thats true. Have you got any idea if it becomes more toe-in/out? I am guessing out?

[kb135]

Did some weighing:

Turns out
Stock 261M in 18x8.5 with 255/35/18 MPSS = 23.2kg
VMR V710 19x9.5 with 255/30/19 MPSS = 23.2kg
Not an error with scale. I triple-checked these. Just co-incidence.

So i guess tightening up my rear end with subframe bushings and altering camber to -2.0* has given me much more traction on rear? Because its quite hard to break traction in 2nd gear in a straight line, and slight to moderately difficult in 1st, from a roll that is. Used to spin like mad in 1st and break traction at 40km/h in 2nd prior to rear end mods. Logs show it's boosting fine... . Will still check for boost leaks anyway, and maybe attend a dyno day and compare. Butt dyno says all is well though Thats what matters most right?

[John_01]

Do you think the new tires may have more grip now they are broken in and started to get some wear?

The rear suspension will gain toe-out when it is compressed. I prefer to call it bump steer.

[BMW86]

I think you need to factor in these variables:
- condition/wear of both sets of tyres
- the road you did the test on
- road surface temperature and conditions (ie. if it has been raining, for how long or how long ago etc)
- tyre pressure
- tyre temperature

From first hand experience these factors can have a noticeable effect

[Pig Farmer]

In addition to ^, you almost certainly increased the MOI of the wheel. Even if we assume the total weight and diameter or the wheel/tire combo stayed the same, the weight of the wheel's barrel (i.e. the heviest part of the wheel) was moved 1/2 inch further from the center of rotation.