Old Tyres

My 308 QV has never had any tire scrub at any speed. This is not normal. There is definitely something wrong there. I would change the tires.

 

I was noticing a push on hard turns in my 328 put new tires on it and it is gone had the factory spec goodyears and changed to bfg kdw big difference no scrub or push.

 

Had that problem when I had over size tires on mine. I have stock 14" wheels and went to the original size 205/70/14's (Michelin Harmony) and problem went away and felt like I had power steering. My tires are only speed rated to 118mph, but rarely reach 100mph on my drives.

 

What does your insurance company think of the 118 mph rating?? Even if you don't drive that fast, they MAY get you on driving the "wrong" tires...

Hans

 

Franco,

I have something similar on mine: At full lock it feels like at least one of the tires needs to skid in order to get around the corner. Only at (near) full lock though.

Tires are brand new. 205/55/16 front and 225/50/16 rear.

Hans

 

Tyre scrub at full lock & very low speed is normal as far as I know and something to do with geometry

There are more important things in life than this (unless you are like the lady from Bristol who was busted for 10 mph on a motorway) in particular eleven year old tyres - there are threads here about how tyres go off after seven years.....


http://ferrarichat.com/forum/showthread.php?t=168931&highlight=tire+age

 

A 328 will be on later 16" rims.....

Low speed handling is indeed sacrificed in the interest of high speed stability IMO...with the specified settings.
Silly I know but your pressures are per the glovebox card?

My old 308GTB has major front/rear stagger on pressure!

I'd do a Track Day or drive with spirit though, and grind those 11 year old tires off, that's past the recommended 5 years duration for street use, no doubt you have some rubber degredation going on......

 

To 14" rim owners:

Please don't cut corners on speed ratings, Goodyear Europe has them and has sent me some for testing they are nice....gatorbacks in our required size....V rated....


Back to 328 tire thread....

 

There's your issue. 11 years is ancient for tires, probably not even all that safe.

I just replaced a set of 7-year old Michelin Sport Pilots with a set of Goodyear Eagle F1's and it now feels as though the car has power-assist steering in car parks. The difference is amazing, and normal roadhandling is far more agile.

 

What was pointed out to me by Goodyear representative was that rubber compounds are CONSTANTLY being improved and developed, so it's always better to run 'fresh' ones.....

*mailing check to Akron, for entire 2007 year product usage..... *

 

My Goodyear techs laugh when I bring in the Trans Am worn down to slicks almost...

"Nice job, you are risking a $30K machine over $200 tires, are you NUTS!!??!!"

I tell them I 'just noticed" the wear bars, and was careful when it rained.......

 

Any car in a turn has scrub. The tighter the turn, or the wider the tire, the harder the scrub. In a turn, each front wheel is covering a different arc, and the inside tire, turning the smallest circle, will scrub the most.

When a car like the 308 has limited slip in the rear axle, anytime the two tires have to turn different speeds, the clutches in the diff have to slip. So in a tight turn, not only do you have scrub on the inside tire, you have torque drag in the rear axle trying to prevent the rear wheels from turning. And as equally as wider tires will magnify the the front tires scrubbing, they will do so also at the rear.

With the two cars here together at one point, I recall having to roll them around in the garage. The car with 205/70's rolled around and turned with ease. This other car with 255's on the front and 245's on the rear is like trying to move a tank around. You can really hear the rubber squeak on the tile floor with that one.

 

I too get scrubbin at low speeds nr full lock on my 86 euro gts, seems like its the norm
Cheers
Mark

 

Just to add to the speed rating blurb, I too am in need of some new boots up front soon. I run good year f1's on the rear and am lookin at putting f1's up front on the 328 but when ! search out good year f1 for the correct size i.e 205 55 R16 they only come in a speed rating of a "W" I think it is which is 168mph? Now I know ferrari quote a ZR tyre would the w be ok? As in theroy the 328 is only capable of 165mph?
Any thoughts?

Cheers
Mark.

 

You mention steering incination being off a bit but adjusting it would affect caster/camber. My understanding is that Caster is the steering inclination so I'm not sure what your alignment guy is telling you? The amount of Caster or steering inclination has a direct affect on how much negative camber gain you get when you turn the wheel. Also effects how hard the steering wheel will try to return to center.

There is also something that goes into effect of steering a car called "Ackerman" and the suspension designers attempt to build in something called "Anti-Ackerman". Let me see if I can explain this. When you go around a corner the front wheels travel a different radius. Imagine a car driving in a circle with paint on the front tires. After you drove in one complete circle you would look at the road and there would be two circles, one from the inside tire and one from the outside tire. The inside wheels are traveling a smaller radius than the outside wheels. In order for the front wheels to track properly the inside wheel must turn in slightly more than the outside front wheel since they are traveling on different raduis.

In performance cars we talk about "Dynamics". Because of the constant changes in what we are asking the car to do, Left turns, right turns, high speed, low speed, go over rough surfaces yet not lean to much etc there is a compromise on any one feature to give us the best overall package. That is why you often have to choose smooth ride over handling. For slow tight turns the best steering geometry would be a solid front axle similar to whats on a kids little red wagon. Not very good for high speeds and also the axle gets in the way of the motor on most cars. Things can and are done on street cars to make the inside wheel turn in more but it is a compromise that can have bad effects on handling during high G turns when you start to factor in body roll, bump steer etc. Get a copy of Carroll Smiths "Tune To Win" if I'm not doing a good job explaining this. I'm a big fan of the series of books and have Prepare,Tune,Engineer and Drive to win and use them as reference and read them over and over.+

I agree with the other posts about limited slip and wide tires also causing this problem too. I'm sure a Chevette does just fine in a parking lot and probably has a lot of Anti Ackerman built in but I wouldn't want to take one around corners at high speed. Now that I think about it I wouldn't want to drive a Chevette under any conditions.

 

I agree. Tires on sports cars should be changed every 4-5 years regardless of wear. Sooner if you have super low profile ones that wear. You'll notice the difference! I can't imagine even driving my Accura with 11 year old tires!


Ken

 

W is the second highest category, second only to Y and yes, that means its rated for 168mph.

A 'ZR' tire is 'safe to 149mph and beyond', but W (up to 168mph) and Y (186mph?) are more specific classifications to clarify the upper limits for serious performance cars. I'm sure the 'W' rating is fine for a 328, unless you live in an area of light traffic and downhill stretches where you often hit sustained speeds in excess of 168mph.

The reality is that there probably aren't any cars with 16" wheels that are going to break the 168mph barrier.

 

Thanks for the info guys

ta
Mark.

 

BigTex, I'd love to find out more about the 14" Goodyear tires that you mentioned. Maybe I'm just dense, or slow, or something, but Goodyear's European web site must be one of the worst I've ever come across. I can't even find a way of searching for tires by size. Do you by any chance have a link to the specific tire that you've got in mind?

Thanks as ever.

 

I'll get Valeria to make some pictures, I hounded them to FIND some!

Not labeled Goodyear though, they own FULDA, made in Germany.......sit tight as we are trying to get a quantity sent over to warehouse in USA market......

Air freighting them turned into a real comedy...they missed the freight quote by, oh......300% or so......

When they hit the dock with FOUR airline logos on them, I thought.."uh oh"........I am working with North American Performance Tire Manager to figure out distribution and pricing, you don't want to pay what I did, for my "samples"!!!!!!

But they DO make the Michelin look like the antique that it is!!!

 

Sadly, the Vintage Racing side gets to ONE tire size short of our requirements......in a 14" Z rated offering!