how to write a for loop to combine several data frame that are made with forward pipe operator in R?

Question

I need to make a new dataframe but I don't know how to use for loop to reduce the repitition.

This is my original data frame

ID t1 t2 t4 t5 t6
1 S B 11 1 1
1 S B 11 2 0
1 S B 12 3 1
1 S B 12 4 1
1 S B 13 5 0
1 S B 14 6 1
1 S B 14 7 1
1 S B 15 8 0
2 S B 11 1 1
2 S B 12 2 1
2 S B 13 3 1
2 S B 14 4 0
2 S B 15 5 1
3 S G 11 1 1
3 S G 12 2 1
3 S G 12 3 0
3 S G 13 4 0
3 S G 14 5 1
3 S G 15 6 1
4 S G 11 1 1
4 S G 12 2 0
4 S G 13 3 0
4 S G 14 4 1
4 S G 15 5 0
5 N B 11 1 1
5 N B 12 2 1
5 N B 13 3 1
6 N B 11 1 1
6 N B 12 2 1
6 N B 13 3 1
6 N B 13 4 1
6 N B 14 5 0
6 N B 15 6 1
7 N G 11 1 0
7 N G 12 2 1
8 N G 11 1 0
8 N G 11 2 1
8 N G 11 3 0
8 N G 12 4 1
8 N G 12 5 0
8 N G 13 6 1
8 N G 13 7 1
8 N G 13 8 1
8 N G 14 9 1
8 N G 14 10 0
8 N G 15 11 1
8 N G 15 12 1
8 N G 15 13 0
8 N G 15 14 0

The following is the code I have written to extract my new data frames:

t=levels(as.factor(df$t4))

df11<- df %>%
  filter(t4==11) %>%
  group_by(ID) %>%
  mutate(num=seq_along(ID)) %>% 
  as.data.frame

df.11.new<- df11 %>%
  group_by(t2, num) %>%
  summarise(mean=mean(t6), count=n())

df.11.new$t7="d11"

I need to repeat this code for all the levels of t4, which are "11", "12", "13", "14" and "15"

and finally combine them all like the following code:

df.all<-rbind(df.11.new, df.12.new, df.13.new, df.14.new, df.15.new)

But I don't know how to write a for loop?