Outer Limits 4x4 Board

Did a couple of hundred kays on stock 205/70R15 HT's the other day (25psi) after years on 235/75R15 MTRs (20psi) and I could swear they are far worse on road.

1) Steering much heavier, hence running them at 25psi. 20psi was prohibitively heavy around town. Likely due to increased rubber on road with HTs vs the flexy lugs on the MTRs?

2) More prone to death wobbles. Never had them on the MTRs - got them badly over 100kph on the HTs. Less unsprung weight and track width?

3) Much harsher over bumps which is readily explained by the slightly higher pressure and lower profile.

Anyone else had similar experiences? Despite the gearing issue and tyre wear, I think I might toss the idea of taking the Zook to Perth on the HTs and refit the MTRs from a stability / driveability point of view....

yeah i used to run 215/70 15 bfg at's which where horrible nowhere near as nice to drive on as my 30*9.5 trepadors especially over bumps and what not, you would find your death wobbles would relate to the balance on your 205's and maybe maybe maybe because it takes more effort to unsettle a larger tyre maybe not sure on that last bit.

I think you are right with your interpritation of what is happening. I used to run 31" BFG mudders on my lwb and it seemed to bump steer very badly and would skate around on wet roads, but then I changed to mungrels and the bump steer went away and you could just power it (ok plant the foot through the floor, cant realy call it power can we!) out of a corner in the wet. I put this down to the lesser amount of rubber on the road.

im finding my 31s handle way better than the 215/75s i had on previously... possibly due to larger contact area and the sidewalls allowing more play. i used to run the 215s at 28psi in summer and 22 in winter.

I find my Claws handle better, even in the wet, than stockies on the Feroza.

When I had the Vit, there was a HUGE improvement in handling and road holding when I went from stockies to 275/75 15 BFG Muddies.

I think you'll find it is your car not the tyres that is creating the death wobbles, The wider tyres you normally run just mask it a little better because of the tram lining affect they have due to the width. The hard steering could be a result of tread design but I find it hard to believe stock tyres would be worse than 235's.

GRPABT1 wrote:I think you'll find it is your car not the tyres that is creating the death wobbles, The wider tyres you normally run just mask it a little better because of the tram lining affect they have due to the width. The hard steering could be a result of tread design but I find it hard to believe stock tyres would be worse than 235's.

Dunno, but the proof's in the pudding. Never had a problem on the bigger MTRs but it was so bad on the HTs that I had to slow down, and steering is most definately heaver - perhaps 40-50% so.

Not sure if what I was experiencing was what people typically call 'death wobbles' though. Basically if sidewinds or a bump resulted in lateral movement of the cab, the car would set up a sway left to right that couldn't be corrected except for braking until it settled then accelerating again, or turning into a long sweeping corner under acceleration which tended to settle it out.

Have had it in similar conditions many times before (do a number of longish highway trips for work in the zook each year) and have never had the problem, or even a hint of it, on the MTRs.

Worst I've had on MTRs at 110km/h is the rear of the car leaving the ground when hitting bumps on off-camber corners and coming back down a few inches sideways. Sounds nastier than it is - results in a little bit of oversteer and helps you around the corner