Paul Posted January 27, 2004 Share Posted January 27, 2004 Right then, after some new tyres for my 18's Anyone got any contacts for somewhere who'll do a good deal on some 275/40/18's and 235/40/18's ? Looking at Goodyear F1's as that's what I've had for years on my 17's. Just getting prices together for the best deal. Paul Quote Link to comment Share on other sites More sharing options...
Bobbeh Posted January 27, 2004 Share Posted January 27, 2004 Tried Ibrar @ Pro Alloys? Quote Link to comment Share on other sites More sharing options...
Branners Posted January 27, 2004 Share Posted January 27, 2004 wouldnt a 275x40x18 really really throw off the rolling radius? I would have thought a 275x35x18 would be better? Quote Link to comment Share on other sites More sharing options...
Paul Posted January 27, 2004 Author Share Posted January 27, 2004 Originally posted by Branners wouldnt a 275x40x18 really really throw off the rolling radius? I would have thought a 275x35x18 would be better? JB, I'm all ears mate, this is what the guy suggested. What do you mean 'throw off the rolling radius' ? Sorry, not up on this, any advice welcome. Paul BTW, got price off Ibrar already, good one but could do with a few to compare. Quote Link to comment Share on other sites More sharing options...
Scooter Posted January 27, 2004 Share Posted January 27, 2004 Paul stock 255/40/17 tyre diameter 25" 275/40/18 tyre diameter 26.7" 275/35/18 tyre diameter 25.6" Quote Link to comment Share on other sites More sharing options...
Paul Posted January 27, 2004 Author Share Posted January 27, 2004 Oh right, so it keeps it closer to the stock radius? what benefit does this have? Paul Quote Link to comment Share on other sites More sharing options...
Bobbeh Posted January 27, 2004 Share Posted January 27, 2004 It means your speedo is more accurate. Quote Link to comment Share on other sites More sharing options...
Paul Posted January 27, 2004 Author Share Posted January 27, 2004 Same profile on the front too? how much would it throw it out? Paul Quote Link to comment Share on other sites More sharing options...
Scooter Posted January 27, 2004 Share Posted January 27, 2004 paul i have a spreadsheet that has been posted up before (i will try and find the previous post), that lets you input wheel/tyres sizes etc and lets you know if they will hit the outer arches or pssibly the shocks + the change in diameter etc. The larger 275/40/18 i had to calculate myself as the spreadsheet just came up with "tyre too tall" when i put the details in. This suggests to me that the tyre will contact the body under compression or on full lock etc. Quote Link to comment Share on other sites More sharing options...
Scooter Posted January 27, 2004 Share Posted January 27, 2004 This thread has the links you need Quote Link to comment Share on other sites More sharing options...
Paul Posted January 27, 2004 Author Share Posted January 27, 2004 Cheers, Ibrar did suggest 275/40/18 though? and the wheels came off a Supra running these tyres? What are the 'normal' sizes for 10 rears and 9 fronts then? Paul Quote Link to comment Share on other sites More sharing options...
Jake Posted January 27, 2004 Share Posted January 27, 2004 Originally posted by Bobbeh It means your speedo is more accurate. You mean "It means your speedo is closer to stock" A slightly increased circumference would actually make the speedo *more*accurate at any speed over 30mph, right? Quote Link to comment Share on other sites More sharing options...
Bobbeh Posted January 27, 2004 Share Posted January 27, 2004 I think stock speedos are supposed to be spot on up to around 60/70 mph.. I know that my wheel size means 58mph now reads as 60 on my speedo. Someone posted a good site where you could estimate the differences etc. http://www.miata.net/garage/tirecalc.html Quote Link to comment Share on other sites More sharing options...
Paul Posted January 27, 2004 Author Share Posted January 27, 2004 That's on Scooters link, speedo accuracy. Sorry, didn't see you'd added it to the bottom So, what works, no rubbing etc.......who's got what? Any other places to try for a good deal? Paul Quote Link to comment Share on other sites More sharing options...
Jake Posted January 27, 2004 Share Posted January 27, 2004 Originally posted by Bobbeh I think stock speedos are supposed to be spot on up to around 60/70 mph[/url] Supposed to be? They aren't spot on though are they? Speedos usually (always?) read waaay over the real speed if you compare them with GPS. Quote Link to comment Share on other sites More sharing options...
Bobbeh Posted January 27, 2004 Share Posted January 27, 2004 Yeah but it lets you play with diff tyre dimentions and compares from stock sizes to new.. so you can have a good idea of what differences new sizes would make Quote Link to comment Share on other sites More sharing options...
Branners Posted January 28, 2004 Share Posted January 28, 2004 dropping to a 35 profile will also make the ride harsher, as does the move to 18s, basically removes the sidewall flex which takes a fair bit of the shock when hitting bumps. The profile is a percentage of the width, so a 35 profile on a 255 would be smaller than a 35 profile on a 285. It does take a bit of thinking about, however you can run a 275x40 and just accept the speedo will be out by a bit, but then as others have said the speedo is always out anyway. Best bet is to try the tyres and get somebody with GPS to sit in the car and tell you the speed the GPS thinks you are doing compared to the speedo. JB Quote Link to comment Share on other sites More sharing options...
Bobbeh Posted January 28, 2004 Share Posted January 28, 2004 TBH John I havent noticed any difference with regard to ride quality with my lower profile tyres.. noise levels are the same, the only noticeable difference is the increased tramlining. Quote Link to comment Share on other sites More sharing options...
Branners Posted January 28, 2004 Share Posted January 28, 2004 I probably dont spend enough time in my supra now but I certainly noticed the ride become harsher with the 18s on and they arent even running high pressures, about 30psi all round. I used to run the 17s at 36psi. But then my suspension is too hard anyway. I also need to get the alignment done as the handling is a little off at the moment. JB Quote Link to comment Share on other sites More sharing options...
Terminator Posted January 28, 2004 Share Posted January 28, 2004 I have used my GPS to check the speed in 5 cars, not one was accurate at 70, all were reading low ie at a speedo indicated 70 most were at 65 to 67 mph GPS. At a GPS 70mph speedo readings were 74 to 77 mph. Most were accurate to 1 mph at 30mph~GPS. This probably explains why most people go through 60 and 70 cameras at 55 and 65. Quote Link to comment Share on other sites More sharing options...
Paul Posted January 28, 2004 Author Share Posted January 28, 2004 Originally posted by Branners dropping to a 35 profile will also make the ride harsher, as does the move to 18s, basically removes the sidewall flex which takes a fair bit of the shock when hitting bumps. As they will go on my potentially 'softer' Mag alloys then maybe this would be a good reason to go with the 40 profile, bit more cushioning for the wheels? I accept that the speedo may be out slightly, but in the right direction as far as gatsos etc go, bearing in mind the type of alloy would this not be a fair trade off? Paul Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.