MarkB Posted February 11, 2011 Share Posted February 11, 2011 I know this topic must have come up before but I need to buy a new set of tyres for my MK3 Spit. I have a GT6 MK2 with 175 70 13 Firestones on as I know 175's are widely recommended as the rolling radius is similar to the original. I have problems with the 175's catching the front and rear arches of the GT6 even though the ride hight is standard. The wheels are the Old Plane Dunlop 5.5 steel wheels and it may have something to do with the offset, not sure. I had a set of 185 60 13 on a 1500 spit years ago fitted to late GT6 / formula ford 5.5 steels. The car sat low and i never had any problems with wheels rubbing. I was thinking of fitting 185 60's again but not sure if the are going to fit within the Spit mk3 rear wings. I am not two bothered about speedo readings because they are not that accurate to begin with and I intend to eventually fit an electrical speedo that picks up on the prop rotation. I have a SAH lemans style bonnet fitted and if needs be can flare the front arches a little to accommodate. The spit has been lowered front and back and I want to use it on some track days. I would like to be able to swap the wheels onto my Vitesse and GT6 if I fancied a change. So after all that, will 185 60 13 tyres fit a lowered Mk3 Spit without rubbing the arches.Cheers Link to comment Share on other sites More sharing options...
Velocita Rosso Posted February 12, 2011 Share Posted February 12, 2011 Try this to compare, but if you have lowered the car then is it the side wall that is rubbing ?http://www.mintylamb.co.uk/?page=tyre.htm Link to comment Share on other sites More sharing options...
starman Posted February 14, 2011 Share Posted February 14, 2011 I run 185/60-13 tires on 13x5.5 steel TR7 wheels I adapted to mount lugcentric on my lowered mk3. No rubbing problems at all, and I didn't even roll up the fender lips. There's more clearance at the rear arches than at the front (and I still have the shorter early swing axles rather than the later longer ones introduced in Feb'73 in the mkIV, after FH25000).As you surmised, offset of the wheels is crucial. Not enough positive offset and you'll rub the arches. Try for at least +18mm (or better yet, +21mm) offset on 5.5x13 wheels to avoid rubbing. Try measuring the backspacing, then solve for offset = backspacing - 0.5*(overall wheel width)= backspacing - 0.5*(rim width + 1 inch) Link to comment Share on other sites More sharing options...
MarkB Posted February 14, 2011 Author Share Posted February 14, 2011 Thanks for that Starman, I'll work it out.Blue Link to comment Share on other sites More sharing options...
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