Operand data type varchar is invalid for subtract operator error

on creating of sp, using the char index, i am getting error as

CREATE TABLE [dbo].[TempTable](
	[ID] [int] NOT NULL, 
	[Name] [nvarchar](128) NULL,
	[ProductCategory] [nvarchar](64) NULL  )
	INSERT INTO TempTable VALUES (1,'Car','Road - Personal')
	INSERT INTO TempTable VALUES (1,'Bus','Road - Public')
	INSERT INTO TempTable VALUES (1,'Boat','Sea - Personal')
	INSERT INTO TempTable VALUES (1,'Ship','Sea - Public')
	INSERT INTO TempTable VALUES (1,'Plan','Air - Public')

--	select * from TempTable 
 
--exec [spTemp] 1
CREATE PROCEDURE [dbo].[spTemp]    
 @ID INT    
AS    
BEGIN    
 DECLARE @SQLQuery AS VARCHAR(MAX) 
  
 SELECT @SQLQuery = 'SELECT [ID],[Name], [ProductCategory] from  [TempTable]
   WHERE   ID = ' + CAST(@ID AS VARCHAR(10))   + ' AND  LEFT(ProductCategory   ,  CHARINDEX(' - ',ProductCategory  ) - 1) IN (''Road'',''Sea'')'
PRINT (@SQLQuery)    
--EXEC (@SQLQuery)
 END



/*

Error
Msg 8117, Level 16, State 1, Procedure spTemp, Line 9
Operand data type varchar is invalid for subtract operator.

*/

Kindly suggest what to change in my query  to get the sp value expected

ShanmugaRaj