Tyre troubles 275/55/20 and air struts and spacers
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Thread: Tyre troubles 275/55/20 and air struts and spacers

  1. #1
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    Tyre troubles 275/55/20 and air struts and spacers

    Hi

    I've been trying to switch my tyres to better off road (we have some fields that get very wet) and bought General Grabber AT3 - but in 275/55/R20. Looking around it seems like quite a few people have that size, although it is about as big as the car can go - apparently.

    Well, on the way back from the fitters, my wife went over a bump and it tore the front suspension airbag with a pop - the new suspension is in and the garage (not the same people that fitted the tyre) point out that there is something like 1mm clearance between the tyre and the suspension.

    We went to try some spacers, I dashed out and bought some locally but the only ones in stock were huge 30mm spacers - but again, lots of people sell these and the 4x4 specialist said that they would fit any L322. But these push the wheel out so far that the garage won't calibrate the suspension because it looks like the tyre will push into the front wing.

    What am I missing here? This has been a really expensive week so far and I still don't have a car! I don't understand how anyone can run that size tyre, or that size spacer.

    Thanks,
    John

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  3. #2
    JUNIOR ROVER MARK_C's Avatar
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    Re: Tyre troubles 275/55/20 and air struts and spacers

    Shouldn't be possible to hit the air bag, maybe the little pin that keeps the bag aligned with the strut but the bag is at least 3 or 4" higher than the top of the tire even bled down.

    See some pictures in my thread from last year:
    https://www.rangerovers.net/forum/6-...core-week.html

    What year truck and what kind of rims are you using? If they are not stock do you know the width and backspacing of the rims?
    M Canning
    Massachusetts, USA
    2006 HSE Bonnati Grey/Charcoal Interior

  4. #3
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    Re: Tyre troubles 275/55/20 and air struts and spacers

    It's a 2007 4.2 supercharged with 20" rims - as far as I know they're stock but can't say for sure. The car's at the garage so don't have any real products, but cropped this from a recent pic with the old 255/55R20 on it.

    If I reach behind the tyre, I can't feel any clearance between the air strut and the tyre - but after the bag had blown last week, there was loads of room; there's a plastic cowl around the top of the strut that looks like it could have been pushed up last week. The garage said that the bag had a clean cut in it, not old age - and it happened when my wife was driving home on tarmac, not off roading.

    This just seems really odd, there must be something basic that's different!

    Here's the pic https://www.dropbox.com/s/oepvx44w5nb4q7d/rr.jpg?dl=0
    2007 4.2 Supercharged

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  6. #4
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    Re: Tyre troubles 275/55/20 and air struts and spacers

    Thinking about it, I have two problems - one is that the rubber is too far in, so potentially this could be the backspacing of the wheel? But OTOH the 30mm spacers are too big - so wouldn't that imply that people who use 30mm spacers all have wheels which could never fit without hitting the suspension tower without the spacer?
    2007 4.2 Supercharged

  7. #5
    JUNIOR ROVER MARK_C's Avatar
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    Re: Tyre troubles 275/55/20 and air struts and spacers

    You certainly don't need a 30 mm spacer, a 10mm (15mm max) spacer would be sufficient. 30 mm would require new studs to be mounted in the rotors as your adding 1.25" of width to the mounting thickness of the rim and there wouldn't be enough exposed threads left to grab the lug nuts. But without knowing the back spacing on the rim you're kind of guessing. My new rims are 8.5 by 20" and have 47 mm of offset (difference between the center of the wheel (4.25" from the lips of the wheel) and the mounting surface where the wheel studs are and they clear by about 3/8" (about 10 mm), stock 2007 20" rims are 8.5" by 20 with 57 mm of offset which places the wheel 10mm deeper into the wheel well than mine are and theres your issue.
    M Canning
    Massachusetts, USA
    2006 HSE Bonnati Grey/Charcoal Interior

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