Civinfo - View Single Post - Tyre Life replace or rotate? (split posts)

TTDegs · 20th March 2007, 01:25

ok.

time to bite the bullet and try to do the numbers with half worn rotations... *gulp*

First up, some assumptions:
tyres on the front wear at a rate of 1mm = 3K miles
tyres on the back wear at a rate of 1mm = 12k miles
tyres start with 7mm of tread
rotate tyres when front tread gets to 5mm ish
replace tyres at 3mm
pair of tyres = £300

6K - front = 2mm wear, down to 5mm. rear = 0.5mm wear, down to 6.5mm. rotate.
front now 6.5mm, rear 5mm. cost to date £0
12K - front = 2mm wear, down to 4.5mm. rear = 0.5mm wear, down to 4.5mm. no point in doing anything. cost to date £0
16.5k - front 1.5mm wear, down to 3mm. rear = 0.4mm wear, down to 4.1mm. replace fronts.
front now 7mm, rear 4.1mm. cost to date £300
22.5K - front = 2mm wear, down to 5mm. rear = 0.5mm wear, down to 3.6mm. no change. cost to date £300
28.5K - front = 2mm wear, down to 3mm. rear = 0.5mm wear, down to 3.1mm. replace front and rear.
front now 7mm, rear 7mm. cost to date £900

So, we're back to exactly where we started - new rubber all round, and we're at 28.5K miles.

double that distance, to save some typing

57k - front now 7mm, rear now 7mm. cost to date £1800
63K - front = 2mm wear, down to 5mm. rear = 0.5mm wear, down to 6.5mm. rotate.
front now 6.5mm, rear 5mm. cost to date £1800
69K - front = 2mm wear, down to 4.5mm. rear = 0.5mm wear, down to 4.5mm. no point in doing anything. cost to date £1800
73.5k - front 1.5mm wear, down to 3mm. rear = 0.4mm wear, down to 4.1mm. replace fronts.
front now 7mm, rear 4.1mm. cost to date £2100

so.

In option1, we did no rotating at all.
at 72K, we had paid out £2400, and had new tyres all round

In option2, we moved the back ones to the front when the fronts wore out.
at 72K, we had paid out £2100, and had new tyres up front, and virtually new ones at the back.

In option3, we rotated the tyres when they hit 5mm, and replaced at 3mm.
at 73.5k, we had paid out £2100, and had new tyres up front, but fairly worn ones (4.1mm left) at the back.

please feel free to spot any mistakes!

(or work out what happens if you rotate ever 3K miles

)

20th March 2007, 01:25	#20 (permalink)
TTDegs Super Moderator Civinfo master Join Date: 4th August 2006 Location: Cardiff Posts: 5,638 Thanks: 0 Thanked 1 Time in 1 Post iTrader: (0)	ok. time to bite the bullet and try to do the numbers with half worn rotations... gulp First up, some assumptions: tyres on the front wear at a rate of 1mm = 3K miles tyres on the back wear at a rate of 1mm = 12k miles tyres start with 7mm of tread rotate tyres when front tread gets to 5mm ish replace tyres at 3mm pair of tyres = £300 6K - front = 2mm wear, down to 5mm. rear = 0.5mm wear, down to 6.5mm. rotate. front now 6.5mm, rear 5mm. cost to date £0 12K - front = 2mm wear, down to 4.5mm. rear = 0.5mm wear, down to 4.5mm. no point in doing anything. cost to date £0 16.5k - front 1.5mm wear, down to 3mm. rear = 0.4mm wear, down to 4.1mm. replace fronts. front now 7mm, rear 4.1mm. cost to date £300 22.5K - front = 2mm wear, down to 5mm. rear = 0.5mm wear, down to 3.6mm. no change. cost to date £300 28.5K - front = 2mm wear, down to 3mm. rear = 0.5mm wear, down to 3.1mm. replace front and rear. front now 7mm, rear 7mm. cost to date £900 So, we're back to exactly where we started - new rubber all round, and we're at 28.5K miles. double that distance, to save some typing 57k - front now 7mm, rear now 7mm. cost to date £1800 63K - front = 2mm wear, down to 5mm. rear = 0.5mm wear, down to 6.5mm. rotate. front now 6.5mm, rear 5mm. cost to date £1800 69K - front = 2mm wear, down to 4.5mm. rear = 0.5mm wear, down to 4.5mm. no point in doing anything. cost to date £1800 73.5k - front 1.5mm wear, down to 3mm. rear = 0.4mm wear, down to 4.1mm. replace fronts. front now 7mm, rear 4.1mm. cost to date £2100 so. In option1, we did no rotating at all. at 72K, we had paid out £2400, and had new tyres all round In option2, we moved the back ones to the front when the fronts wore out. at 72K, we had paid out £2100, and had new tyres up front, and virtually new ones at the back. In option3, we rotated the tyres when they hit 5mm, and replaced at 3mm. at 73.5k, we had paid out £2100, and had new tyres up front, but fairly worn ones (4.1mm left) at the back. please feel free to spot any mistakes! (or work out what happens if you rotate ever 3K miles )