Tire Test: Is the value-priced X Comp H/P a 200tw contender?

Hello guys. Tire Rack website shows 8.5 inches tread width for the Bridgestone Potenza RE71RS and I see that you have 9.8 inches tread width here. What's going on?

Yep, 9.8 is Section Width for each tire, not tread width.  Good eye!

Missed that in the proofing process.  That chart was created after the story left my hands and the mistake wasn't caught on review. 

Sigh...

I like these tires, but m y Golf-R understeers bad.   Despite the -3.5° camber and 38 PSi hot (these values are from the front tires) it understeers  bad. The RE71RS over heat quickly, and the "V" markers on the front tires are trespassed. I got the thickest anti-roll bars front and rear, they are 25.6mm in the rear and up front too. 

What can I do ? 

Gerhard

In reply to GAM :

I haven't owned a FWD in 20 years now, so this may not work the way I think it should, but try disconnecting your rear sway bar. My Miata would not turn in to save its life, due to really limited camber. Popped the rear end links off the sway bar, and that helped turn in quite a bit.

In reply to GAM :

I would have left the rear bar bigger than the front. Have you tried messing with your toe settings?

Fcyaa said:

Hello guys. Tire Rack website shows 8.5 inches tread width for the Bridgestone Potenza RE71RS and I see that you have 9.8 inches tread width here. What's going on?

Yes, thanks for catching that. I've adjusted the chart in the story.

In reply to GAM :

Understeers bad could also be overdriving a corner; does the car swap ends quickly, or does it only plow all the time? 

Also, more rear stiffness (generally) will let the back end come around easier.  The faster you go the more the car turns from responsive to squirrelly as you up rear stiffness, though.

Let's talk about rear stiffness and FWD for a moment.

It doesn't work the same as on the typical well-balanced (50/50) RWD platform like a Miata or BMW.  In those cases, altering relative roll stiffness front-to-rear will affect the car through out the entire cornering phase -- entry, mid, and exit.  It does this by altering how much weight is transferred at each end.

With the typical nose-heavy FWD car, it's pretty easy to transfer *all* of the weight at the rear of the car in a corner.  That's what causes the rear to top-out the suspension and come off the ground.  Once you have enough rear roll stiffness for this to happen, either through anti-roll bar or springs, you cannot further alter the balance of the car.  You *can* alter when this happens in a turn, however.  Stiffen the rear enough and it begins rotation super-early in the corner, understeers in the middle and then allows for earlier throttle application on exit to balance the tendency for oversteer. 

This is commonly called setting the car up just this side of "killing you on entry" so you can get early drive off the corner.  Go too far, however, and you're that "tank slapper guy".  We've all seen that guy.

Hmmm,..I sense a tech story here....

Andy Hollis said:

Hmmm,..I sense a tech story here....

In reply to Andy Hollis :

Great stuff, what I've experienced in my Mini, though if you drive in the rain with the car set up to "kill you on entry" it just might.