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348 rear tyres

Discussion in 'Technical Q&A' started by jkuk, Mar 19, 2004.

  1. jkuk

    jkuk Formula Junior

    Nov 3, 2003
    259
    Wirral, UK
    Full Name:
    John K
    Guys,

    I have tried searches without success, but does anyone know how wide I can fit the rear rubber on the stock 9J rim of a 348.

    Current rubber is 255/45

    Thanks
     
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  3. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,426
    socal
    275 45 17


    you can go 305 on 18's

    You can go 245's in the front

    You can wiggle these numbers by changing ride heights but watch the chassis rake changes
     
  4. Miltonian

    Miltonian F1 Veteran

    Dec 11, 2002
    5,960
    Milton, Wash.
    Full Name:
    Jeff B.
    JK: From my experience (which is only based on replacing tires in the stock sizes) DO NOT put on new rear tires without also replacing the front tires. I put new rears only onto my 348, same brand, same size, same speed rating, same tread pattern, and the car handled very, very badly until I replaced the half-worn front tires as well.

    Your post does not suggest that were going to replace the rears only, I'm tossing out the info just in case.....
     
  5. NC348

    NC348 Karting

    Feb 18, 2003
    154
    Houston, TX
    Full Name:
    James I. Movich
    Jeff,
    i did rears only on mine w/O any problems at all.
     
  6. Miltonian

    Miltonian F1 Veteran

    Dec 11, 2002
    5,960
    Milton, Wash.
    Full Name:
    Jeff B.
    NC: Interesting! What brand tires were you replacing? Miine were Bridgestones. Replacing only the rears made the car undriveable, it was all over the road.
     
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  8. NC348

    NC348 Karting

    Feb 18, 2003
    154
    Houston, TX
    Full Name:
    James I. Movich
    P zeros (asymetricos)

    no noticable difference at all. car tramlines just as wildly as before! HA!

    no, really. it made no change at all. and i was leary about doing it as i had read your note on that from post months ago. tires have been on for a couple of months now, and car drives great.
     
  9. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,426
    socal
    NC + Milton,

    The problem is not the car or the tires but the alignment. Good tires/new tires can mask some misalignment. If you want some awesome change corner weight the car and rest the alignment. Also, before you blame your tires try maintaining the now almost 15 year old suspension in some 348's. There are mnay cars out there that dogtrack , squirm on heavy braking, shimmy at speed and wander at speed due to suspension compliance and alignment. With slick race tires the small changes are even more noticeable. We can use one brand front and one brand rear just to get sizes right and even have different softnest compounds and still tune the car for the tires just fine. IT is your set-up believe me. Also the best alignment is worthless if the old rubber bushings put your suspension all over the place.
     
  10. 95spiderman

    95spiderman F1 World Champ
    Silver Subscribed

    Nov 1, 2003
    10,333
    ny
    put 275 on stock rims and 295 on 10" rims. both better than stock without problems
     
  11. 98TDFSpider

    98TDFSpider Rookie

    Dec 29, 2003
    22
    Before I bought my 355 I had a 993 Porsche that I replaced the rear tires only. For the first hundered miles or so I thought there was a major suspension problem or something in the rear. It turned out I just needed to wear off the mold release from the new rear tiress. After a few hundred miles everything returned to normal. I suspect that was your problem too -- and that replacing the fronts just gave you 4 slippery tires so it felt "normal" as opposed to only having 2 rear slippery tires.
     
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  13. jkuk

    jkuk Formula Junior

    Nov 3, 2003
    259
    Wirral, UK
    Full Name:
    John K
    Thanks guys for the info.

    I need to replace all 4 tyres as I have a different make of tyre in every corner of the car.

    The offside has relatively new tyres, the near side are nearly worn.

    Car feels all over the road, and I suspect some alignment problems, mainly because only the offside has been replaced.

    I plan to change them all and then get the suspension fully re-aligned.
     
  14. jkuk

    jkuk Formula Junior

    Nov 3, 2003
    259
    Wirral, UK
    Full Name:
    John K
    Guys,

    There doesn't seem to be a lot of choice in the 275/45 profile, or even 265/45 for that matter.

    If I go the 275/40 (265/40) profile route, am I upsetting the balance of the car ?

    Would I need to change the fronts to /40 profiles in order to maintain the rake of the car.

    Thanks
     
  15. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,426
    socal
    Buy the tires you like. Put them on car. Set rake per manual I.e. stock ride height. Then lower evenly using motion ratio per manual and Lower your car to where you like it. Then take to alignment shop. If you follow my instructions you will not go wrong.
     

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