New tires pull on uneven roads

[jpinoh]

I recently changed out my original Goodyears on my 'stang 99GT and put on a set of Kumho Ecsta 712's. I read through the various reviews on TireRack.com and these seemed like a good choice for this car.

But I notice these tires are a lot more sensitive to road imperfections. Here in northern OH we have a lot of rough roads from the winters and I spend a lot time correcting the car with steering input to keep me in my lane. The standard Goodyears had little tendency this way.

I didn't change the alignment yet, and this will be changed next week when I put on the Griggs CC plates. Griggs gave me some numbers to set for street use, and a higher camber number for open tracking.

So is this wandering a function of the tire design mostly, or is there something in an alignment that dials this sensitivity out? Only one review at TireRack mentioned this sensitivity, and no other Mustang owner did, so I'm wondering if it's my car.

I have played with tire pressures a little - it's about the same at 30, 32 and 34 psi.

My current setup:
Griggs PHB/TA and SFC; new LCA's and rear coilovers going in next month
CC plates going in next week
Stock springs/shocks still - no change in rates or ride height (so this shouldn't be a case of bump steer up front).

Thanks for any insights -

--JPinOH

[mean81GT]

are the tires wider than the ones you had before? is the tire a softer compound? there are many things that could be causing this, more than likely it is the tires themselves.

[wally6761]

i can't really speak for the tires, but i can tell you my car does that also because of the wheels being so wide (consequently the tires being wide). it was the same way when i drove my 85 TA.
not much you're going to be able to do about without getting narrower wheels, like 7'' wide or less.

[lowerswill]

I have the same pulling issue with my stang. In every groove or rut in the road my car pulls and on back roads I sometimes get tired of working to keep my car in the lane or on the road.

Everyone I have every talked to about this issue says it is all about the size of your tire, not the tire itself. I am not changing to a skinny tire just to make roads better. They should just re-pave the roads for me

[jpinoh]

The tires are the same size as the originals - 245-45-R17's, and on the original GT 17" rims that came with the car.

I could see the same degree of pull for these tires, but since it is more with the new ones, that's the reason for my questions. Maybe the different tread pattern is the reason - these Kumho's are a little like the Goodyear Aquatreads for tread pattern.

Thanks all.