new tires & traction control

[jawz101]

I dunno if they are related but this evening I hit the onramp and noticed some lag. I looked down and my traction control was showing some slip. After I hit the gas again the car lunged forward again.
I kept on flooring it every now and then and if I was around 70 or so and hit the gas the car would shift normally but as it was accelerating I saw the traction control light blinking like crazy until I let off.

New tires are Toyo Proxes ST 255/50/18 VR18. I don't think that matters as much as if there is a correlation if the shop could have done something else back there, or if it is just a fluke that a new issue is happening recent to the change.

Thanks

[FordNut]

Rear tires need to be a little taller than the fronts or traction control won't like it.

[CanadaMarauder]

My P225/60R16 winter tire causes various traction control problems due to change in over all tire diameter.Syptoms exactly the same.No problems with TC turned off. http://www.net-comber.com/tirecalc.html this site may help if you did change from stock size....hope this helps you out

[TripleTransAm]

Rear tires appear to be 5% shorter sidewall-wise than the stock size. Do you have these tires all the way around? If so, the fronts will end up 8.5% taller than the stock tires. That will mess up the traction control.

[jawz101]

fronts are stock still. i'll probably switch those out soon to get the respective proportional Toyo tires
guys at tire shop ran calculations and said they should be same diameter though diff size

[jawz101]

ew... they are different. Maybe a new tune w/ tire size change is necessary?
Toyo 255/50/18 diameter 28.04
KDWS 245/55/18 diameter 28.61

[TripleTransAm]

Right, so instead of the 3% difference in circumference (and speed) with respect to the front tires (at stock dimensions), you are operating at only 1.7 % difference. So I guess that must be outside the boundaries of acceptance by the T/C system.

To keep your current rear size, you'd probably need something like a 245/45 up front to achieve the 3%. Hopefully they have that size available.



Edit: my excel spreadsheet was only accounting for one thickness of the sidewall, not both. So the suggested numbers above in my post may be very wrong.

[looking97233]

The Toyo Proxes ST is avail. in 255/45/18 which is what I am going to try later this spring on the front with the same as you (255/50/18) in the back.

Rod.

[Vortech347]

To be damn near right on the money compared to the stock sizes you need 255/45/'s front and 255/50/18's rear. the 285/50's on the back of mine are a hair bigger than they should be. Note this is ST's And to let you know they are kinda loud on the freeway so be ready for it. They are really a "light truck/SUV" tire as per their website. Handle GREAT though

[wchain]

255/55R18s in the rear are OK with T/C and stock fronts.

[04MRADR]

I'm surfing the net like crazy the last few days since I need new tires. The only problem with a lot of the P235/50/18 tires is they do not have matching P245/55/18 rears. Go onto the TireRack.com web site and sort by tire size. There are many P235/50/18 tires including Bridgestone Potenza S-03 Pole Position, Continental ContiSportContact 2, Dunlop SP Sport 9000, Goodyear Eagle F1 GS-D3, Michelin Pilot Sport, Pirelli PZero Rosso Asimmetrico and many others including both the original equipment BF Goodrich g-Force T/A KDWS and the new g-Force T/A KDW2. But when you look up size P255/55/18 there was only 3 tires listed. They were the Pirelli PZero Ross Asimmetrico, BF Goodrich g-Force T/A KDW 2 and Dunloip SP Sport 5000 Symmetrical. There was nothing listed in the P245/55/18 except the original KDWS g-Force tires. If as other members say you need to go bigger in the rear then the only match you seem to be able to get is the KDW 2 BF Goodrich tires, same size as originals in front but P255 versus P245 in rear. By the way, has anybody been able to get tires that don't wear on the inside edge in the front or down the middle in the rears? By the way, the original KDWS had treaadear ratings of 400, the new KDW 2 have only 300.

[rayjay]

The front tire wear is caused by the alignment specs used at the factory. It can be corrected by using Carfixers alignment specs. A search here will turn up those specs for you.

[MENINBLK]

The rear tires need to be 5% taller than the fronts.
If you can achieve this difference, the TCS will be happy.

[TripleTransAm]

Yes, 5% is correct (not 3% as I initially wrote above).
I tried the calculation at work when I first read this and kept coming up with 5%, so I had no idea why my spreadsheet at home had kept churning out 3% until I looked through it tonight and saw that it was only accounting for 1 sidewall thickness and not 2, in calculating the overall tire height.

Apologies for the misinformation.