Triumph Repair: rear tire wear, swing axles, rear leaf spring

Question
QUESTION: Howard, I have a 1972 spitfire 4 I put new tires on it 3 months ago. On the rear tires I am showing signs of wear on the outside edges. The `rear tires don't always look straight up and down. They are angled at times. Looks like the bottoms of the tire are angled towards the middle of the car.  What do you suggest I do to help fix this before my tires get all chewed up.

ANSWER: Hi Mark,
The Spitfire has "swing axles" meaning the wheel is attached solid to each axle and each axle has only one "U" joint in close to the differential. When the car is light in the rear, (low on fuel, not much in the trunk and one person or two light people and a strong rear leaf spring) the car sets up high which allows the camber to be "positive" (wheels lean out at the top) If you were to fill the fuel tank and load the trunk and / or put two heavy people in the car then the spring will be compressed and the wheels will be negative camber (Wheels lean in at the top) Yes, this does effect the ware on the rear tires.
An added factor is if there is a problem with the rear suspension that causes the rear wheels to move forward causing a "toe in" condition, that will tend to ware the outside of the tires also and cause the camber to go positive on driving and negative on deceleration.
Best thing to do is to check for any loose play in the rear suspension and load the car by adding and subtracting weight in the trunk to keep as close to zero camber when you sit in the seat, and rotate your tires often. It is the design of the rear suspension. Only other option is to try to find an "In Car" adjustable air shock to fit in place of the original shocks.
Howard

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QUESTION: Hi Howard I took a look today and my radius arms are pushing thru the plate behind the seats tearing thru the metal. I guess it time to weld and fabricate. have you ever seen this happen before? thanks for your help

Answer
Mark, You need to remember that the normal life span of a car in the 70s was about 5 years and your car is now 35. That's 700 years in human life spans. A lot of these cars were not garaged so you need to look closely for signs of rust under the car. Triumph has been out of business for 27 years but you can still buy almost every part for the car here in the US and even body parts. The cars are fun to drive but keep in mind it is not a car, it is a hobby.
Howard