Marathon Blowouts and Question
I suffered four blowouts on our '97 TM 3023 over about 16,000 miles. All occured in 90 plus degree weather on Interstates (three in Florida) traveling at about 62 mph. The first, an original Carlisle could be explained by the age of the tire. Three others were approx 2 year old 14" GoodYear Marathons. Once I was told by the Good Year people that the cause was a defective valve stem made in China. I keep the pressure at 50 psi and check before I travel each day. When not in use the wheels are off the ground and have tire covers. Why the blowouts? The Marathons can't seem to take the weight + the speed + the heat. It's dangerous to change a tire on the side of an interstate. So, I will take state highways as much as possible.
My son, a civil engineer, who works in highway design tells me that Florida interstates have a "coarse coat" for safety. This coarse coat causes more tire friction enhancing safety but leading to more heat. The trailer wheel hubs and tires are slightly less warm on country roads, about the same warmth as my Tundra tires.
To decide what to do, I measured the spaces I have in the wheel wells with a compass and with current tires in place. They are:
4 and 3/4" above 14" Good Year
3" in front of wheel (3 o'clock)
1 and 5/16" behind wheel (9 o'clock)
3/4" from wide part of tire to fender skirt
Weighing TM
Weight on rear axle with weight dist. hitch properly attached 3200 lbs
Weight on rear axle with same unattached 3140 lbs
I was surprised that the difference was not greater.
So, that's 1600 lbs per tire when TM is fully loaded and that includes food, clothing, rear window awning, side awning, AC, hanging cabinet, battery, 3 gal in hot water tank, 1 bike. Spare(s) are in truck. A wheel expert told me that 1600 lbs "is pushing the envelope." The limit for Marathons is 1760 lbs.
I am seriously considering going to Kumho Part #857 Size 205 R14C 8D and using metal valve stems from Napa as shown in previous threads. (Part #90-416 Tubeless Clamp-In Tire Valve TR 416 1 and 1/4" lenght, Fits .453 and .625 rim holes).
An acquaintance recommended 15" 205 75 R15 Trail Master. I cannot find any specs or evaluations about these on the web. Has anyone had experience with these tires? Do they have a greater weight bearing capacity that the 205 Kumhos? I would be happy to know.
My thanks to experts Frenchy, Shrimp Burrito, Wm Tire and others for their helpful discusssions and advice.
97 TM 3023
04 Tundra
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