Order of reactivity of alkyl halides in Sn1 reactions

**Problem::** Predict the order of reactivity of the following compounds in SN1 reactions .


i) $\ce{PhCH2Br}$ 


ii) $\ce{Ph2CHBr}$ 


iii) $\ce{PhMeCHBr}$ 


iv) $\ce{Ph2MeCBr}$ 


Answer::


SN1:iv>ii>iii>i


Reason:: SN1resonance due to phenyl groups.


I didn't understood why it doesn't consider loss of planarity as *two or three phenyls groups can't arrange themselves in a plane around one carbon atom* because of **ortho hydrogen clash** with each other which will no allow 
**Effective resonance**


Please provide some examples or explanation to it
Here is an example of loss of planarity in a compound with 3 phenyl groups![enter image description here](https://i.stack.imgur.com/Nve5u.jpg)


