Firestone Tire & Rubber Co. financing reports continue to show the effects of a $110 million writeoff related to phasing out tire production at some plants, with losses shown for the second quarter and first half.

Firestone said yesterday the loss for the quarter ended April 30 was $44.4 million, and the six-month was $37 million.

Excluding the writeoff, Firestone net income from operations for the quarter was $28.6 million (50 cents a share) compared with $39.3 million (68 cents) for the corresponding 1977 period.

"Second-quarter earnings from operations without the writeoff reversed the declining quarterly earnings trend of the previous three quarters and were the highest since the second quarter of 1977," company officials said.

Because actual expenditures related to the phaseout of domestic and foreign plants are being spread over for several years, the effect of the writeoff on cash flow was minimal in the second quarter, the company reported.

Firestone officials said second-quarter sales of $1.2 billion and first-half sales of $2.3 billion set records, topping the billion and $2.1 billion for the comparable periods last year.

Although Europeans operations were unprofitable because of "continuing industry overcapacity and its effect on pricing," results in South America, Africa and Asia-Pacific areas all were ahead of 1977, the company reported.

Deere & CO., the farm and industrial machinery maker, yesterday reported a sales gain of 18 percent for the first half of its fiscal year ended April 30 and a 4 percent rise in profit.

First-half net income was $136.9 million ($2.26 a share) on sales of $1.909 billion, up from $132.2 million ($2.20) a year ago on sales of $1.618 billion.

Second-quarter net income was $88.7 million ($1.46) on sales of $1.19 billion compared with $92 million ($1.53) a year earlier.

The company pointed out that earnings were exceptionally strong in the second quarter last year, but sales for the quarter were up 11 percent this year. Farm machinery sales for the half were up 36 percent at $390 million. Farm machinery sales were up by 14 percent.