關於英文wear的用法問題。?

杯子裡「有」半杯水「剩下來」。（可能態度消極，或失望，因為在意的是消失的那部分）
杯子裡「有」半杯水。（可能態度積極，抱希望，因為在意的是現存的這部分）

left =剩下
寫作時的視覺角度（態度）決定了要不要用這個字（受詞補語）。
但兩句的事實相同：都是「有」半杯水。

wear = the capacity for withstanding continuous use without such damage

Old things were relegated to the bedrooms because there was plenty of wear left in them.

see p.1957 New Oxford American Dictionary Third Edition

這個字的意思是正面的，後面有無left，不會改變它的方向。
句裡的there was...表示一個過去曾經「...存在」的事實。

這就是語言之中的"習慣面".在英語裡面:

wear就像是中語裡面的"歲月"一樣可以是"過去(使用過的)".也可以是"未來(預期可用的)".

"plenty of wear left" 是"還可被磨很久"的意思?

回到你的問題:
(a) There is plenty of wear in the tires.
(b) There is plenty of wear left in the tires.

1. 文法上都是正確的
2. 意思卻是大大不同.(a)是輪子有很多磨損(b)是輪子痕可以磨很久.

(a)There is plenty of wear left
=it is in a good ,useful condition
=The machine will stand any amount of hard wear
=still suitable for everyday use;
=in constant use
=still looks strong for a long time
=可用好長一段時間

(b)There is plenty of wear in the tyres
=wear and tear,damage, loss in value, from normal use
=The tyres are showing signs of wear
=no "left"
=There's not much wear left in these tyres.所餘用途無幾 !
=loss in value ; with the word (left)
=cannot be used (=worn) much longer;
=輪胎不可以用很久.