Some of you have probably heard me rattle on about choosing a thinner racing tyre so it will get up to operating temp.

Here's a reason for using a thinner tyre on the street too, especially on the front of your beetle.

By thin I'm suggesting using a 185 on a performance beetle rather than 205 wide tyre.

I copied this from The Tire Rack Website.

Aquaplaning or Hydroplaning.

Hydroplaning happens when one or more tires is lifted from the road by a wedge of water that gets trapped in front of and under a tire as the vehicle drives through water. Hydroplaning most frequently occurs during heavy rainstorms when water creates puddles on the highway or expressway. In addition to the accompanying splash and scaring the heck out of the driver, hydroplaning typically causes the steering wheel to jerk and the vehicle to abruptly pull towards the puddle.

The speed at which a tire hydroplanes is a function of water depth, vehicle speed, vehicle weight, tire width, tread depth and tread design. It depends on how much water has to be removed, how much weight is pressing down on the tires and how efficient the tread design is at evacuating water. While deeper water, higher speeds, lighter vehicles, wider tires, less tread depth and less efficient tread designs will cause tires to hydroplane at lower speeds; all tires will be forced to hydroplane at some speed.

As a rule, tread design affects hydroplaning resistance at high speeds and in deep water. Tread compound affects wet traction at lower speeds or in shallow water.

CYA CT

If you want more grip get a better tyre not a wider one.

My 2 cents (rounded down). CT

CT,
I have to agree with you there. Had exactly what the quote in your post says happen. Was travelling along the F3 with Hamo in his bug more or less at the speed limit ( 70mph ) when the steering wheel suddenly jerked in his hands. You felt the front of the bug lift up, the tyre noise went away and we just floated uncontrollably down the freeway. Anyway ended up crossing lanes as thats the way the water was flowing across the road diagonally over say 100metres. Then the front came back down and away we went again. It scared the bejesus outta Hamo and im sure i shat myself. I thoroughly do not recommend it to anyone. Have Fun. Keith.

mmmmmmm .... bugga thats never good... what width wheels were thay

Hi,
That was with 195 or 205 60 series, not sure which one.
Keith.

shite! ....my baja had 215s on the front before the accident and i am now putting 195s on the front to improve steering.....it has 235s on the back:o

i aquaplaned in a 85 ford fairlane at 80kmh into the oncoming lane of the hwy, scared the shit out of me definetly.

with 4 1/2 deg neg camber I'm probably only running a foot print the size of a 185

Good points CT.

So are you happy with your new tyres.

I aquaplaned in my old Datsun 1600 doing 60kph! 205s with not much tread. I did a 360 over the median strip on Mona Vale road in Sydney and went backwards up someone's driveway. Didn't hit or damage anything, and drove off shaking like a leaf!!!

Tread depth is also a factor in aquaplaning. Anything beyond 80% worn does a couple of things. It will increase your wet braking distance and lower the speed at which your car starts to aquaplane.

Craig, the new tyres are excellent. They're not slippery when cold. I tried to induce understeer on my outlap to heat them up but they just gripped. They gripped so well the car was leaning more in corners and heating up the outside edge or the outside tyres, even with 2.5 neg camber. The trouble is the extra body roll was causing more inside rear wheel spin than ever before. I tightened the rear bar all the way and it reduced the wheelspin. But I seriously need to tune that our or get a limited slip diff. Perhaps a bit more front swaybar and I'll put the stiffeners back on.

CYA CT

NB a bit more tyre pressure in wet conditions can open the grooves in the tread a little as well as putting more pressure on the middle of the tread contact patch which helps water get pumped out the sides.

Low tyre pressures are really bad in the wet. The pressure is put on the sidewalls and the water is trapped under the centre of the tread. The also lowers the speed at which your car will start to aquaplane.

good to hear CT


Interesting to note that you are now putting back the suspension products you removed, its amazing what a good set of tyres can do for your car

Your lap times will now get even better, leave the engine alone and now start playing with the gearbox. Fine tune your ratio's and maybe invest in a Quaife or LSD.

Cheers
Craig T

Hi Craig,

I don't know if the stiffeners work or not. I removed them after talking to someone who said the stiffeners caused his car's body to crack where they bolt on. At the time my front suspension was very hard due to the adjustable front bar not working properly. I could easily imagine the shock the beam was transmitting to the body. Now I've softened my front suspension and got rid of the understeer it's a good opportunity to see if the stiffeners do anything. I will bolt them on between runs at wakefield park and rate them by the seat of my pants.

Have you done a back to back test with and without the stiffeners?

Have you done a back to back test with a stock-type whiteline bar vs and adjustable bar?

With regards to gear ratios that's where I draw the line. Gearboxes are big money and I'm not that serious about racing. Besides Jak and I have the same boxes and that makes racing eachother more fun. I have another one of those boxes that I'm going to give to Paul so he can join in.

CYA CT

Back to the topic.

Wheel and tyre weight is another good reason not to go too wide. Weigh a standard tyre and rim then weigh your combination. Imagine how much extra strain you're putting on components like bearings and suspension joints.

Consider too that the suspension travel is less and the loads are increased due to more speed and more grip and bigger brakes.

Also another performance objective is to reduce the unsprung weight. I saved almost 2 kilos per wheel by changing from my last set of tyres to my new set.

While you've got the scales out weigh a Porsche cookie cutter then weigh a contemporary after-market alloy.

Back to Craig.

It's interesting that your tyres rubbed the sway bar. Mine rub the shock and shock tower unless I adjust out the steering stops. I guess that's the difference between running 14 inch and 16 inch rims.

You seem to have lots of steering lock available. How did you achieve that? The spacers I have between my hubs and wheels helped my steering lock but I still can't do a U-turn on a regular street.

CYA CT