Car Budget

The costs of my car are as follows -
Loan cost: $16 490 at 15% over 5 years
Tyre price: $130 per tyre, need replacing every 18 months
Fuel consumption: 6.4L per 100km
Insurance cost: $1295.16 per year
Vehicle registration cost: $641.90 per year

My income is $1057.69 per week. I can only spend half of this ($528.85) or less on my car. I need to calculate how much I will be spending on my car.
Loan repayments
SI = PIT
SI = 16 490 x 0.10 x 5
SI = $8 245
Total amount to be repaid = P + SI
Total amount to be repaid = $16 490 + $8 245
Total amount to be repaid = $24 735
Weekly repayments = Total amount to be repaid / [52 x T]
Weekly repayments = $24 735 / [52 x 5]
Weekly repayments = $95.13 per week
Tyre price
Car requires 4 new tyres every 18 months, tyres cost $130.
Every 18 months I will spend 4 x $130 on tyres = $520
To find weekly repayment I will find monthly repayment
$520 / 18 = 28.89
To find yearly repayment I will multiply this by 12
28.89 x 12 = $346.67
Now to find weekly repayment I will divide this by 52
$346.67 / 52 = $6.67
Tyre cost per week = $6.67
On average I travel 200 km per week. If fuel costs $1.38 per litre and my car uses 6.4L per 100km how much will I spend on fuel per week?
Fuel consumption per week = 6.4 x 2
Fuel consumption per week = 12.8L
Fuel cost per week = 12.8 x 1.38
Fuel cost per week = $17.66
Insurance costs $1295.16 per year
Insurance cost per week = $1295.16 / 52
Insurance cost per week = $24.91
Vehicle registration costs $641.90 per year
Vehicle registration costs per week = $641.90 / 52
Vehicle registration costs per week = $12.34

Total cost of car per week = $95.13 + $6.67 + $17.66 + $24.91 + 12.34
Total cost of car per week = $156.71
I have successfully met my budgeting needs of spending less than $528.85 on my car per week.