Chris`I Posted December 17, 2011 Share Posted December 17, 2011 Running 40 profile with no probs. Running 245/45/18 and 235/40/18 on the front no problems whats so ever. Ive done more than 20k miles on them too. Im replacing them for 225/40/18s as they are a hell of a lot cheaper. I personally havent found any of this traction control problems alot of people bang on about. Maybe my car is different? Clearly you've never understoon any of the posts I've made explaining how TC works then? You are not finding any problem as your difference in percentage terms of rolling radius front to rear keeps the stagger that the TCS expects. Should you run tyres with the same rolling radius front to rear you will understand what we are talking about. As for the OPs original question, yes you can run a 40 profile. I did on my 18s on the 350z as Falkens have somewhat soggy sidewalls and I was recommended to do so. You need to keep the OEM front to rear stagger in rolling radius though. So use 40 profile all round and you'll be fine AFAIK, but keep to staggered widths such as 225F and 245R. Quote Link to comment Share on other sites More sharing options...
sukh13 Posted December 17, 2011 Author Share Posted December 17, 2011 Running 40 profile with no probs. Running 245/45/18 and 235/40/18 on the front no problems whats so ever. Ive done more than 20k miles on them too. Im replacing them for 225/40/18s as they are a hell of a lot cheaper. I personally havent found any of this traction control problems alot of people bang on about. Maybe my car is different? Clearly you've never understoon any of the posts I've made explaining how TC works then? You are not finding any problem as your difference in percentage terms of rolling radius front to rear keeps the stagger that the TCS expects. Should you run tyres with the same rolling radius front to rear you will understand what we are talking about. As for the OPs original question, yes you can run a 40 profile. I did on my 18s on the 350z as Falkens have somewhat soggy sidewalls and I was recommended to do so. You need to keep the OEM front to rear stagger in rolling radius though. So use 40 profile all round and you'll be fine AFAIK, but keep to staggered widths such as 225F and 245R. Thanks for the info On the point that the miles will rack up faster, how much difference are we talking? E.g. for every ten miles on the odometer, the smaller profile tyres will only travel XX miles. Quote Link to comment Share on other sites More sharing options...
Chris`I Posted December 17, 2011 Share Posted December 17, 2011 Think it made my speedo over-read by a couple of MPH. Between 245/45/18 and 245/40/18 there is a 25mm difference, or ~3.7% Quote Link to comment Share on other sites More sharing options...
sukh13 Posted December 17, 2011 Author Share Posted December 17, 2011 So if we say 4% For every 1000 miles on the clock, you will only be travelling 996. Not that much effect? Or am I missing something? Quote Link to comment Share on other sites More sharing options...
Chris`I Posted December 17, 2011 Share Posted December 17, 2011 No, for every 100 it reads on the clock you will have done ~96, so at 1000 miles, you'll have really done 960 Quote Link to comment Share on other sites More sharing options...
Dblock Posted December 17, 2011 Share Posted December 17, 2011 Running 40 profile with no probs. Running 245/45/18 and 235/40/18 on the front no problems whats so ever. Ive done more than 20k miles on them too. Im replacing them for 225/40/18s as they are a hell of a lot cheaper. I personally havent found any of this traction control problems alot of people bang on about. Maybe my car is different? Clearly you've never understoon any of the posts I've made explaining how TC works then? You are not finding any problem as your difference in percentage terms of rolling radius front to rear keeps the stagger that the TCS expects. Should you run tyres with the same rolling radius front to rear you will understand what we are talking about. As for the OPs original question, yes you can run a 40 profile. I did on my 18s on the 350z as Falkens have somewhat soggy sidewalls and I was recommended to do so. You need to keep the OEM front to rear stagger in rolling radius though. So use 40 profile all round and you'll be fine AFAIK, but keep to staggered widths such as 225F and 245R. Yes I did. But why does everyone keep to 45's then? They are more expensive, less choice and they have a bigger sidewall to flex. And the OP was asking about 40 profiles so what you on about? Quote Link to comment Share on other sites More sharing options...
Chris`I Posted December 17, 2011 Share Posted December 17, 2011 People keep the OEM sizes as thats what Nissan fit and it keeps the speedo correct. The car does not give a fig what size tyres you are running, what it cares about is the relation of the radius of the front wheel when compared to the rear. If you keep that relationship as it expects then the TCS will be happy, stray from its programmed size and it will have a fit. Many people fail to comprehand the relationship between wheel size (diameter of tyre), width and profile. All of them affect the radius of the tyre. So saying "fit a 40 profile and you'll be fine" is not right unless you specify the right width for the given diameter (in this case 18"). The problem many fall for is they fit tyres with the same radius front and rear. Then the car thinks the rear wheel is spinning faster than it is all the time, so TCS kicks in. The rear tyres radius needs to remain larger than the front so the car thinks they are spinning at the same speed. You could fit 15's if you wanted so long as the relationship front to rear remains (forgetting they wont fit over the brakes) Quote Link to comment Share on other sites More sharing options...
glrnet Posted December 17, 2011 Share Posted December 17, 2011 Ok I understand about the relationship of radii between front and rear ref TCS, but what is the formula or how can I find out the tyre sizes that will keep the speedo as near as poss to "true" as well for the following wheel sizes? Front 19 x 8.5 Rear 19 x 10 People keep the OEM sizes as thats what Nissan fit and it keeps the speedo correct. The car does not give a fig what size tyres you are running, what it cares about is the relation of the radius of the front wheel when compared to the rear. If you keep that relationship as it expects then the TCS will be happy, stray from its programmed size and it will have a fit. Many people fail to comprehand the relationship between wheel size (diameter of tyre), width and profile. All of them affect the radius of the tyre. So saying "fit a 40 profile and you'll be fine" is not right unless you specify the right width for the given diameter (in this case 18"). The problem many fall for is they fit tyres with the same radius front and rear. Then the car thinks the rear wheel is spinning faster than it is all the time, so TCS kicks in. The rear tyres radius needs to remain larger than the front so the car thinks they are spinning at the same speed. You could fit 15's if you wanted so long as the relationship front to rear remains (forgetting they wont fit over the brakes) Quote Link to comment Share on other sites More sharing options...
Dblock Posted December 17, 2011 Share Posted December 17, 2011 People keep the OEM sizes as thats what Nissan fit and it keeps the speedo correct. The car does not give a fig what size tyres you are running, what it cares about is the relation of the radius of the front wheel when compared to the rear. If you keep that relationship as it expects then the TCS will be happy, stray from its programmed size and it will have a fit. Many people fail to comprehand the relationship between wheel size (diameter of tyre), width and profile. All of them affect the radius of the tyre. So saying "fit a 40 profile and you'll be fine" is not right unless you specify the right width for the given diameter (in this case 18"). The problem many fall for is they fit tyres with the same radius front and rear. Then the car thinks the rear wheel is spinning faster than it is all the time, so TCS kicks in. The rear tyres radius needs to remain larger than the front so the car thinks they are spinning at the same speed. You could fit 15's if you wanted so long as the relationship front to rear remains (forgetting they wont fit over the brakes) I did state the sizes though? You just want to argue over nothing? Quote Link to comment Share on other sites More sharing options...
Chris`I Posted December 18, 2011 Share Posted December 18, 2011 Ok I understand about the relationship of radii between front and rear ref TCS, but what is the formula or how can I find out the tyre sizes that will keep the speedo as near as poss to "true" as well for the following wheel sizes? Front 19 x 8.5 Rear 19 x 10 Get on a tyre size calc site. Stick in the OEM tyre size and then the new tyre size and compare. You want to aim as much for as little difference as possible. http://www.etyres.co.uk/tyre-size-calculator.htm Front: 660mm - 225/45/18 (OEM) 654mm - 245/35/19 (New wheel) 6mm difference or 0.91% Front: 678mm - 245/45/18 (OEM) 675mm - 275/35/19 (New wheel - stretched a bit?) 682mm - 285/35/19 (New wheel - not stretched?) 3mm difference or 0.44% OR 4mm or 0.59% respectively for 275 and 285 I did state the sizes though? You just want to argue over nothing? Sorry I was refering to the "most members" bit. Agreed that your tyre sizes are fine, thats what I said in my first reply, that you dont have a problem as your tyres sizes are fine. The point I was making was to the OP and that you cant blindly put 40 profiles on, you need to understand the relationship first, which no one has explained. People usually come unstuck by not understanding this and just swapping tyres willy nilly Quote Link to comment Share on other sites More sharing options...
nzr350z Posted December 18, 2011 Share Posted December 18, 2011 Do believe that speedometers have to be within 3% of reading correct,if you drop to 40's will completly throw speedo out therefore you wont know what speed you are actually doing. Quote Link to comment Share on other sites More sharing options...
Dblock Posted December 18, 2011 Share Posted December 18, 2011 Ok fair enough. I've understood your previous posts about tc and assumed you still thought i didn't get it. I don't see the point in sticking to 225/45/18 as they are way more expensive with less choice. Odd size maybe? I know what your saying with the speedo but I can live with a small percentage. Ok I understand about the relationship of radii between front and rear ref TCS, but what is the formula or how can I find out the tyre sizes that will keep the speedo as near as poss to "true" as well for the following wheel sizes? Front 19 x 8.5 Rear 19 x 10 Get on a tyre size calc site. Stick in the OEM tyre size and then the new tyre size and compare. You want to aim as much for as little difference as possible. http://www.etyres.co.uk/tyre-size-calculator.htm Front: 660mm - 225/45/18 (OEM) 654mm - 245/35/19 (New wheel) 6mm difference or 0.91% Front: 678mm - 245/45/18 (OEM) 675mm - 275/35/19 (New wheel - stretched a bit?) 682mm - 285/35/19 (New wheel - not stretched?) 3mm difference or 0.44% OR 4mm or 0.59% respectively for 275 and 285 I did state the sizes though? You just want to argue over nothing? Sorry I was refering to the "most members" bit. Agreed that your tyre sizes are fine, thats what I said in my first reply, that you dont have a problem as your tyres sizes are fine. The point I was making was to the OP and that you cant blindly put 40 profiles on, you need to understand the relationship first, which no one has explained. People usually come unstuck by not understanding this and just swapping tyres willy nilly Quote Link to comment Share on other sites More sharing options...
Freebird Posted December 18, 2011 Share Posted December 18, 2011 Anyone ever thought about turning off their traction control? Quote Link to comment Share on other sites More sharing options...
coldel Posted December 18, 2011 Share Posted December 18, 2011 Just buy the right sizes... You have invested some serious amount of money into a nice looking and lovely to drive sports car. I spent over £30 on a night out the over night over the bar, probably the difference in cost for one of the four tyres - just skip a couple of nights out per year and you are almost at the point of recovering the cost. These things are going to be on your car for a fair while, why buy something that doesn't look right (and they dont on 18s) and could at some point cause other problems if you get it wrong as chris has pointed out. You can play around with upgrades, uprevs, colours, looks, badges whatever, but just get the tyres right first - if anything those would be the things I would throw the money at and get right. Quote Link to comment Share on other sites More sharing options...
Dblock Posted December 18, 2011 Share Posted December 18, 2011 Just buy the right sizes... You have invested some serious amount of money into a nice looking and lovely to drive sports car. I spent over £30 on a night out the over night over the bar, probably the difference in cost for one of the four tyres - just skip a couple of nights out per year and you are almost at the point of recovering the cost. These things are going to be on your car for a fair while, why buy something that doesn't look right (and they dont on 18s) and could at some point cause other problems if you get it wrong as chris has pointed out. You can play around with upgrades, uprevs, colours, looks, badges whatever, but just get the tyres right first - if anything those would be the things I would throw the money at and get right. 40's look much better than the 45's. Quote Link to comment Share on other sites More sharing options...
coldel Posted December 18, 2011 Share Posted December 18, 2011 Just buy the right sizes... You have invested some serious amount of money into a nice looking and lovely to drive sports car. I spent over £30 on a night out the over night over the bar, probably the difference in cost for one of the four tyres - just skip a couple of nights out per year and you are almost at the point of recovering the cost. These things are going to be on your car for a fair while, why buy something that doesn't look right (and they dont on 18s) and could at some point cause other problems if you get it wrong as chris has pointed out. You can play around with upgrades, uprevs, colours, looks, badges whatever, but just get the tyres right first - if anything those would be the things I would throw the money at and get right. 40's look much better than the 45's. Not on 18s on an unlowered Zed they dont, huge gaps in the wheel arches, looks just wrong...but, personal opinion I guess. Quote Link to comment Share on other sites More sharing options...
tprice Posted December 18, 2011 Share Posted December 18, 2011 just buy whatever ones you want!! Quote Link to comment Share on other sites More sharing options...
coldel Posted December 18, 2011 Share Posted December 18, 2011 just buy whatever ones you want!! Just make sure you dont sacrifice the cars handling as chris outlined for the sake of a few quid...thats kind of the crux of what people are saying. Quote Link to comment Share on other sites More sharing options...
tprice Posted December 18, 2011 Share Posted December 18, 2011 absolutely!! but it does depend on who you are and how you drive! thats why i put grippy stuff on mine! so it can stay on the road! Quote Link to comment Share on other sites More sharing options...
Freebird Posted December 18, 2011 Share Posted December 18, 2011 In all seriousness tyres really are the most important part of any car Quote Link to comment Share on other sites More sharing options...
coldel Posted December 19, 2011 Share Posted December 19, 2011 In all seriousness tyres really are the most important part of any car +1 Buy what you want, but dont buy tyres because they are cheap. That should not be a consideration. Quote Link to comment Share on other sites More sharing options...
Stew Posted December 19, 2011 Share Posted December 19, 2011 Being Devils advocate here...... Most of us have to have some kind of cost consideration or everyone would have £2k worth of tyres. Falken, Toyo, Vreds etc etc are all chosen because they perform well enough for your needs at a good price. Running a lower profile has been done by several people successfully so if by changing the size that means they save a few quid or can 'upgrade' to better rubber then I personally don't seeing it as being an issue. My advice would be to know what you are putting on. If you buy langyong tyre factory ditchfinder xls+ then that's fine but don't expect them to perform. If you want to run 40 profile then know the pros and cons before purchasing as it'll cost you twice if you get it wrong. Anyway, that's my 2p. Quote Link to comment Share on other sites More sharing options...
Dblock Posted December 19, 2011 Share Posted December 19, 2011 In all seriousness tyres really are the most important part of any car +1 Buy what you want, but dont buy tyres because they are cheap. That should not be a consideration. But the 40's are cheaper for no difference in grip. Unless your running super sports and blizacks your not best person to be giving that advice. 100% agree Stew. There is much better tyres in the 40 profile including my favourite Goodyear F1a2. Quote Link to comment Share on other sites More sharing options...
glrnet Posted December 19, 2011 Share Posted December 19, 2011 Thanks Chris Ok I understand about the relationship of radii between front and rear ref TCS, but what is the formula or how can I find out the tyre sizes that will keep the speedo as near as poss to "true" as well for the following wheel sizes? Front 19 x 8.5 Rear 19 x 10 Get on a tyre size calc site. Stick in the OEM tyre size and then the new tyre size and compare. You want to aim as much for as little difference as possible. http://www.etyres.co.uk/tyre-size-calculator.htm Front: 660mm - 225/45/18 (OEM) 654mm - 245/35/19 (New wheel) 6mm difference or 0.91% Front: 678mm - 245/45/18 (OEM) 675mm - 275/35/19 (New wheel - stretched a bit?) 682mm - 285/35/19 (New wheel - not stretched?) 3mm difference or 0.44% OR 4mm or 0.59% respectively for 275 and 285 I did state the sizes though? You just want to argue over nothing? Sorry I was refering to the "most members" bit. Agreed that your tyre sizes are fine, thats what I said in my first reply, that you dont have a problem as your tyres sizes are fine. The point I was making was to the OP and that you cant blindly put 40 profiles on, you need to understand the relationship first, which no one has explained. People usually come unstuck by not understanding this and just swapping tyres willy nilly Quote Link to comment Share on other sites More sharing options...
nzr350z Posted December 19, 2011 Share Posted December 19, 2011 On a slightly different note.Wont fitting non standard size tyres invalidate any insurance on the vehicle,as they are not factory recommended sizes? Quote Link to comment Share on other sites More sharing options...
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