High Speed Breaking with Khumos V700

[V10TT]

Guys, I have Khumos V700s in the rear and Pilots in the front, car is lowered with Eibachs; I have noticed under hard braking from 160+ mph the car wobbles in the rear, to the point where I have to grab the steering wheel with both hands and go easy on the brakes to keep it under control. Could it be the mixed tires on it (pilots up front and Khumos in the back)? It does handle fine under normal braking, or from lower speeds (100 mph) but when I hit it hard after a blast to 160mph or so it wobbles in the rear...I don't remember the car doing this when I had Pilots on all four corners.
I will align it this weekend and see if it gets better. Just wondering if anybody out there with this combination of tires has had a similar experience.
Thanks!

 

[AviP]

I doubt it's the Kumhos. Most likely it's the fact that the rear end is getting very light due to the hard braking and is probably trying to come around. The Viper is front heavy to start with.

 

[PhoenixGTS]

The Viper is front heavy to start with.

GTS Viper has more weight on the rear axle than the front axle. I believe the split is 49/51% front/rear (changing w/fuel load of course). Remember the Viper is really a mid-engined car with a forward engine placement (like a Panoz LMP race car). The entire engine is behind the front axle.

 

[Casey]

I never had that when I had Kumhos on the back of mine and Pilots up front.
And I did those runs quite often.

 

[V10TT]

Could it be I need alignment after lowering the car?

 

[CAS]

Could it be I need alignment after lowering the car?

If you haven't had that done, you need to. Also, the Viper is not front-heavy, but is very sensitive to weight-transfer, although I think your problem is very likely alignment related. Also, I wouldn't mix tires; I've only seen one guy in the VRL successfully mix tires. It's generally discouraged to do so.

 

[Jack B]

I would look at the rear toe adjustment, I also did not see the year of the car, could it be the recall issue, thus, a failure in the linkage attached to the differential.

 

[viper spray]

Put Kumhos up front also.

 

[PhoenixGTS]

Put Kumhos up front also.

They do not make a V700 in the proper size for the front. The 275-30-18 is too short and they do not make a 275-35-18 in the V700. I am going to try mixing in Ectsa MX 275-35-18 on the front as they are the same height as the V700 in 335-30-18.

I saw my new tires mounted today and yep the V700 look funny with no rim-protection ridge.

 

[V10TT]

Guys, had the car re-aligned this morning and it cured it!
thanks!