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MG MGB Technical - Wheel and tyre size

Could anybody tell me what the largest/ widest wheel and tyre size that can be fitted to a 79 MGB GT without any modifications to the bodywork, the ride height will be dropped to the chrome bumper hight. Could I fit 15 x 5.5 but what tyres would be needed so the speedo remains correct?
a goldup

I'm using 15 by 6 inch dayton wire knock off wheels, 25 positive offset with 195 by 60 tubeless tyres. I finally found some one who could balance tyres on them (hip hip hooray!). I also have a set of alloy superlights, 15 by 6, 24 positive offset. Tyres are Michelin energy savers. The low rolling resistance thing actually works.
This brings the total rotating circle (wheel plus tyre) to the same as factory standard. No speedo error, presuming your speedo still works. The lower profile tyre is of course much more responsive.
No guards alterations, or interference at all. You can get wider with different available offsets and compensating spacers as there is about one or 0.75 inch clearance on the bump stop side. About half an inch on the outside at the 2/3rds mark on the rear wheels. However 195 is really as wide as you want to go, starts to look a bit hot rod'ish over that. plus it is plenty.
This is on a 75 dropped to chrome bumper height.
Peter Sherman

15" 175 65 +2mm +0.7%
15" 185 65 +9mm +3.1%
15" 165 65 -4mm -1.4%
PaulH Solihull

Have a look at this site for more info than you ever thought you'd need about tyres & wheels, including a calculator that shows you how closely your planned choice of wheels & tyres matches your original wheel running radius. You don't have to be spot on: speedos aren't terribly accurate and you can check it afterwards with a satnav.

Malcolm Eades

I use Michelin Pilot P195/60R15 on my car. The speedometer is plenty accurate. I'd recommend installing a Panhard rod on the rear axle to prevent the sidewalls of the tires from rubbing against the inner lip of the wheelwell if you like to drive hard on winding mountain roads.
Stephen Strange

Dear All, whom have contributed to this thread, Thanks. It was with your thoughts, and those others from other sites that now contributed to my currently running Superlites ( minilite replicas, made here in Australia.) On my 1972 MGB GT. They are shod with Yokohama 185 X 60 in 15" format. It is true that 195 gets a bit too wide with tramlining on some surfaces, and dependant on the tyre tread design. Yokohama apparently give good grip dry and wet, but can wear more quickly that say Michelin equivalents. But the price was right. on the first test drive it really did feel more solid. but highlights other areas of the suspension I have still not addressed. King pin and upper swivel bush, and the suspension pan bushes. all else I have replaced, rear springs uprated slightly lower,( bushes, Urathane) slightly lower front springs, and telescopic dampers all round. Why,? the leverarms are perfectly ok if working well. I agree, it was an offer I could not refuse! I'll keep you posted. regards Mike
J.M. Doust

Not only are lever-arms perfectly OK if working well, they are far better than the telescopics that were available for many years, if not now. Not only do most telescopics give an extremely hard ride unless adjustable and on their softest setting, they also (in my experience) last no longer than lever-arms and are a lot more expensive to replace. After replacing mine once, when they went again I went back to lever-arms.
PaulH Solihull

This thread was discussed between 16/11/2010 and 26/11/2010

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