Tire Choice

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Tire Choice

Post by DBR330GT » Fri Sep 17, 2004 11:18 pm

Hi Guys

I think my Pirelli Cinturato P5s may be ancient. My whole car shutters above 85 mph- I had this same problem in my 328 GTB that was caused by worn tires and was fixed with new ones. The shuttering is not localized to one wheel and makes no funny noises- its the whole car that shutters.

Anyway I was thinking of getting Pirelli P4000 Super Touring tires- 215/70WR15 (no whitewalls) just like the size I have now. I read Tom's piece on the Symmetry tires but I would like for the tires to be Pirellis.

What do you think?



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Post by horner » Sun Sep 19, 2004 11:50 am

You may need new tires, and additionally have other problems. Check your tie rods, suspension bushings, etc. Also, even w/ new tires make sure that the wheels are properly balanced and inflation is to spec. As to tires, I use Michelin XWX 205 x 15, but there is probably a Pirelli sized somewhere around 205 or 215. I stay w/ 205 to avoid any potential fender, etc rubbing, but the aspect ratio on some 215 may be just enough lower than originals to allow no worries. Tom has something on this site somewhere, and the Ferrari Club of America site's Tech section has numerous tire topics covered for vinatge Ferrari's. LJH
Jack Horner, 1966 330 GT 2+2 Series II, s/n 8325 (x-1981 Mondial 8, s/n 36213)

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Post by fuiszt » Sun Sep 19, 2004 2:01 pm

The biggest issue with lower profile tires is the loss of ground clearance-seems to be plenty of clearance for the tires themselves.
With mine, new tie rods made it steer like a sports car instead of a boat (dollar-wise the best upgrade so far for my car)-but the car really ought to be super solid at 80 to 90 mph, so something must be wrong. I'm not sure its such a good idea to be flying around on ancient tires anyway. Maybe get a sharp eyed person to follow you and see if there is a visible wobble with one of the back tires.
64 330gt 2+2 #6413

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Post by DBR330GT » Sun Sep 19, 2004 7:24 pm


The car seems to steer real well- good turn in etc. The car is solid going over bumps. The car doesnt lean too much in corners. The shocks arent bouncy. In other words the car feels great until I hit 90 mph (which I only do briefly just to see what it is like). The tires do feel hard to me when i am driving.

Since they need to be replaced anyway, is it reasonable just to start there and if that cures the problem then just keep an eye on things?


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Post by tyang » Mon Sep 20, 2004 10:02 pm

Hi Dan,

I think a switch to new tires will be a good place to start. All too often, I see cracked/dry-rotted tires on Ferraris at the shows, and amazed that people drive on these things. I can understand trailering a car a car to a show on these things, but driving at any speed is just too risky. Having a blowout or loosing pressure is bad enough on a regular car, but Ferraris are so low, you could easily tear out the exhaust, or grind a nice spot on your oilpan if a tire goes flat.

Make sure the tire shop knows how to balance your wheels. Look up some of the articles I wrote about balancing the Borannis, and the special hub I machined to get the balancing right.

'63 330 America #5053

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