Notices
Series I Wheels, Tires, Brakes & Suspension

Changing from 225-45-18 to 225-40-18

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old 11-08-2009, 02:30 AM
  #1  
Registered User
Thread Starter
 
peanut187's Avatar
 
Join Date: Mar 2009
Location: South Africa, Jhb
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
Changing from 225-45-18 to 225-40-18

I want to know what the effects will be if I change from the stock 225 45 18 to 225 40 18, the problem is that the tire sellers tell me the RX8 has an odd tire size so the original size tires are double the cost, I'm in South Africa so you may not have the same problem in the country you might be in. So the point is i want to get a 40 profile to keep the cost down.
Old 11-08-2009, 04:19 AM
  #2  
Relax baby!
iTrader: (3)
 
rx 8speciale's Avatar
 
Join Date: Oct 2008
Location: Nurburgring driver, Germany
Posts: 1,006
Likes: 0
Received 0 Likes on 0 Posts
the only downside is the tackometer will be off by like 1 or 2 mile so when it say 50 you really are at 48 . thats it ..... go for the cheap tires!
Old 11-08-2009, 04:24 AM
  #3  
Registered
 
REDRX3RX8's Avatar
 
Join Date: Jun 2007
Posts: 713
Received 22 Likes on 21 Posts
Wheel one centimeter lower, and 3.5% reduced final drive. I'm installing 225/40r18 Hankook v12 K110 on purpose to get more acceleration and less sidewall flex. I use my scan gauge II for speed anyway so I don't care if the speedo is off.

Last edited by REDRX3RX8; 11-08-2009 at 04:26 AM.
Old 11-08-2009, 04:40 AM
  #4  
I made some poos
iTrader: (1)
 
Juice's Avatar
 
Join Date: Sep 2005
Location: Pittsburgh, PA
Posts: 841
Likes: 0
Received 0 Likes on 0 Posts
You can also try and get a 245/40/18 tire to keep the overall diameter close to stock.
Old 11-08-2009, 06:35 AM
  #5  
Momentum Keeps Me Going
 
Spin9k's Avatar
 
Join Date: Sep 2002
Location: Colorado
Posts: 5,036
Likes: 0
Received 4 Likes on 4 Posts
235/40-18 works just fine and is closer than 225/40 but a bit smaller than the perfect match 24/40-18
Old 11-08-2009, 01:32 PM
  #6  
2005 Black RX-8 GT 6M
 
CarAndDriver's Avatar
 
Join Date: Jul 2006
Location: San Jose Area
Posts: 6,350
Likes: 0
Received 0 Likes on 0 Posts
Search "Tire Calculator" on Google. You can see what the differences will be.
Old 11-08-2009, 04:53 PM
  #7  
Registered User
 
rxGhost8's Avatar
 
Join Date: Apr 2007
Location: Houston Tx
Posts: 9
Likes: 0
Received 0 Likes on 0 Posts
Putting 225/40s will also make you car ride a little rougher. I got smaller tires installed on my car and its not much rougher but you will notice
Old 11-09-2009, 02:11 AM
  #8  
Registered
 
InTune's Avatar
 
Join Date: Feb 2009
Location: South Africa, CT
Posts: 11
Likes: 0
Received 0 Likes on 0 Posts
I've got 225/40 Bridgestones on mine. Yes, it's literally half the cost compared to the original size, and no real difference other than ride comfort - it's a slightly harder ride, but there's no other downside. I've noticed a number of 8's with the same profile.
Old 11-09-2009, 03:06 AM
  #9  
Rotor User
 
fastlaneracing's Avatar
 
Join Date: Nov 2007
Location: Sweden
Posts: 838
Likes: 0
Received 0 Likes on 0 Posts
I have used 225/40-18" and 235/40-18" and both dimensions make minimal changes from 225/45-18". The small changes there is is actually (in my mind) to the better.

225/40-18" - Slightly better acceleration, better looks (not so mutch tire sidewall), less sidewall flex, slightly harder ride.

235/40-18" - Same acceleration as stock dim., same comfort as stock dim., slightly better grip.

Im going to stick with 235/40-18" cheaper tires (more auto makers uses this dimension) and the rest is close to stock or better.
Old 11-09-2009, 03:15 AM
  #10  
Registered User
Thread Starter
 
peanut187's Avatar
 
Join Date: Mar 2009
Location: South Africa, Jhb
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
thanx for all the advice, def going to help me alot.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
airlive
New Member Forum
5
06-28-2020 07:46 AM
mdl0209
Series I Trouble Shooting
14
05-23-2019 05:46 PM
Danield97
Series I Trouble Shooting
1
09-30-2015 05:59 PM
jasonrxeight
RX-8's For Sale/Wanted
2
09-30-2015 01:53 PM
XianUnix
Series I Trouble Shooting
6
09-29-2015 03:48 PM



You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: Changing from 225-45-18 to 225-40-18



All times are GMT -5. The time now is 02:12 PM.