# Tire Size - 16" or 17"? Effect on perfornance?



## pgames38 (May 12, 2005)

It's looking like we'll buy a 2006 xt. I've read that a new options package includes 17" tires. We might get the package, or just get 17" tires separately. 

What advantages will I gain from having 17" tires, performance and safety-wise (apart from the boost in speed)? Any experiences or advice from anyone will be appreciated, and thanks!

pgames38


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## Sergei_dekker (Jun 4, 2005)

better stability(something which the Xty needs) and slightly reduced body roll....But remember your off road capabilities will suffer abit when using 17' inch rims as u will have to fit lower profile tyres and fuel consumption too will suffer but its kinda negligible


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## aussietrail (Sep 24, 2004)

Fuel consumption should be the same, but your speedo will be out, hence the reading you can get for your fuel consumption will not be accurate.

I suggest you re-calibrate your speedo if you go up to 17" rims.


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## patrick39 (May 24, 2005)

aussietrail said:


> Fuel consumption should be the same, but your speedo will be out, hence the reading you can get for your fuel consumption will not be accurate.
> 
> I suggest you re-calibrate your speedo if you go up to 17" rims.



If the overall diameter is the same, shouldn't the speedo also be the same?


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## ValBoo (May 19, 2003)

There you go :thumbup: 

Talking about wheel/rim size (ie Internal Diameter of tire) does not mean much when we don't know about the tire profile used!

Indeed, Pat is right, 16" or 17" rims may end up with same tire outside diameter depending on profile used.

as in this example:
on 16" P215/65R16 = 27.00" tire OD
on 17" P215/60R17 = 27.16" tire OD
(pretty close to being the same and therefore no effect on speedo)

it is easier playing around with this:
tire calculator 




patrick39 said:


> If the overall diameter is the same, shouldn't the speedo also be the same?


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## aussietrail (Sep 24, 2004)

That is correct Pat and Marc, it depends on what 17" tyre is chosen.


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## L.Lee (Jul 24, 2005)

If given a choice, I would pick the 17" rim as I travel mostly on highway and
city street.

The lower profile (the aspect ratio between the thickness of the tire and
the width of the tire) tires with directional tread tend to have better straight
-line control when travel in high speed. Of course depend on the tire you
use. Comfortable level may not change significantly between 65 and 60 
series. My 3-week old x-Trail come with 16" rim and I can live with that after
I replaced the stock tire with Bridgestone Dueler H/P (harder side all with
directional tread). Side note: The x-Trail steering weight tends to be on the
light side, may be it is common for SUV.

I am using 215/45 17" on my other car, an MPV. It reduces body roll a little, 
with a firmer but smoother ride (less bounce due to harder and lower side
wall), and very stable on high speed. But need to watch out when driving
over hump. On the downside, it is more prone to aquaplan (spelling?) and has
a shorter tread life - may not be significant for a 60 series..

Cheers,


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## thetimster (May 6, 2005)

*My $0.02 worth... not sure if its Canadian or Australian $ though...*

If it will mostly be city driving, 16 and 17 rims might not make that much difference even if the tire is not adjusted to the same height. If you match the outer diameter using the tire calculator, the lower profile 17 inch tires will give you more stability... because generally the larger rim tires are wider than the smaller rim tires. Stability is also affected by offset... i.e. whether the rims sit outside, just at or inside the wheel wells. If you get it from the dealer, than I assume it will be the same offset. If not, make sure the offset is for the X-trail (between 35 to 45 should be OK if I'm not mistaken). If you will be doing off-roading or driving on bumpy roads, the larger rims will have more bounce on the bumps if you are getting lower profile tires to match the outer diameter of the stock 16 inch tires. So if that's the case, it might be better to get wider 16 rims and wider 16 inch tires to match the outer diameter of stock.

I drive mostly in the city. My 20 inch rims feel only slightly bouncier than stock. But at 245 width, acceleration is slightly less because the rim/tire combo is heavier. It feels more stable the rare times I'm on the highway though. 

Again, I'm no expert... these are just tidbits I gathered from my own experience in modifying my car. So really, just $0.02 worth!


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## aussietrail (Sep 24, 2004)

Hi Guys,

Thought I will revive this thread and up the size a little 

I scored 18x7.5 alloys and now looking for tyres to suit.

What is the most common size for that size alloys?

Is it 245/45R18 or 255/45R18

These will be low profile performance tyres with a higher load rating (i.e. equal or higher than 98 of the factory tyres we have)


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## Canada's Far East (Jun 15, 2005)

*Facts & Figures*



aussietrail said:


> Hi Guys,
> I scored 18x7.5 alloys and now looking for tyres to suit.
> 
> What is the most common size for that size alloys?
> ...


Hi Jalal:

Can't comment on the *"most common"* (other members with 18s may respond) but here are some facts and figures for your consideration:

*Compared to your OEMs* the:

*245/45s *

will change your Overall Diameter from 685.8 mm to 677.67 mm. This is a Diameter Difference of 1.19%, which is within acceptable standards.

will give you a speedometer difference of 1.207% too fast - - and you're probably already too fast  

*255/45s*

will change your Overall Diameter from 685.8 mm to 686.56. This is a Diameter Difference of 0.12%, which is well within acceptable standards. Most folks in the business recommend staying within 3% of the diameter of the original tire. 

will give you a speedometer difference of 0.103% too slow. 

As you can see, both are quite close to the OEMs (with the Plus sizing taken into account) but the 255s seem to have the edge. It's going to be a costly investment, so you want to get it as right as possible first time around.

Cheers = Roger


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## aussietrail (Sep 24, 2004)

Thanks Roger, I'm also leaning towards the 255's however the recommended rim width for such a wide tyre is 8-9.5 inch (mine are only 7.5 inch wide)

Am going to the tyre shop this weekend to see which tyres would fit best and yes, they're VERY expensive indeed being the low profile performance tyres. I am actually trying to buy them second hand.


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## notaire (Aug 10, 2004)

Are the 255 to large when full steering ?


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## aussietrail (Sep 24, 2004)

notaire said:


> Are the 255 to large when full steering ?


Nope, because the rolling diameter is the same. I have seen an exy with 20" with no problems at full lock, but there was almost no rubber on the alloys LOL That's how low profile tyres the were.


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## notaire (Aug 10, 2004)

aussietrail said:


> Nope, because the rolling diameter is the same. I have seen an exy with 20" with no problems at full lock, but there was almost no rubber on the alloys LOL That's how low profile tyres the were.


I understand that the rolling diameter is about the same but tire width is increase from 215 to 255, so at full lock, tire may rubbing fender.


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## aussietrail (Sep 24, 2004)

notaire said:


> I understand that the rolling diameter is about the same but tire width is increase from 215 to 255, so at full lock, tire may rubbing fender.


Wont be a problem. In my case am increasing from 235 to 255, as I currently have 235/60/16 on the exy.

The only thing am concerned about is the tyres sticking out of the fender a bit too much but I'll check that at the time of fitting. If it is the case, I will be going with 245s.


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## SmallSteps (May 3, 2006)

Hi Jalal,

I think you will find the 255s do indeed stick out of the fenders, i.e. if you are using the an offset of 35 - 40.

Ken


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## aussietrail (Sep 24, 2004)

SmallSteps said:


> Hi Jalal,
> 
> I think you will find the 255s do indeed stick out of the fenders, i.e. if you are using the an offset of 35 - 40.
> 
> Ken


Thanks Ken, the alloys have exactly the same offset as the factory one. They're 40 offset indeed. I also suspect they gonna stick-out too much and I don't really want to see that.


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## Terranismo (Aug 31, 2004)

Jalal, I have 255/55R18 tires on my wheels and they do rub slightly under full steering lock. The rears also rub when under full load in cornering.

I'm planning on going back down to 17 inch wheels and tires, once I run these bare. The unsprung weight is killing my gas consumption and making it slower to acelerate.


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## SilverShadow (Jan 24, 2006)

I am planning to change my tire set up from 235/60R16 stock springs to 225/55R17 with H&R sports lowering springs. 

The car will be lowered by 1.5 inches, what do you think guys? TIA 

80% on road
20% pothholes


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## flynn (Jun 23, 2006)

SilverShadow said:


> I am planning to change my tire set up from 235/60R16 stock springs to 225/55R17 with H&R sports lowering springs.
> 
> The car will be lowered by 1.5 inches, what do you think guys? TIA


Any particular reason for doing that? If top-class handling is important to you then you probably won't get it in an SUV no matter what you do to it. If you just want a 4x4 estate then something like a Quattro or Octavia 4x4 might suit you better.


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## SilverShadow (Jan 24, 2006)

To improve the handling and better appearance are the main reasons  without sacrificing comfort and fuel mileage ( hope my calculations are correct).


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## aussietrail (Sep 24, 2004)

surprisingly as it may sound and since I fitted the 18" alloys to my ride (upgraded from 16") my fuel consumption has improved heaps. I used to get 11.5LT/100kms city driving, now I get 10LT/100kms in exactly the same driving conditions. The ride comfort has not been impacted at all with the low profile 245/45R18 tyres but the difference in handling is amazing.


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## aero (Sep 16, 2006)

aussietrail said:


> Hi Guys,
> 
> Thought I will revive this thread and up the size a little
> 
> ...



Bro, the tyres width is abit too wide. 245 or 255 with 7.5" rims will make "donut" shape (the tyres are abit out compare to the rims). Which is abit wasted in performance wise. The tyres wont seat perfectly. For performance tyre (especially low profile tyres), better avoid the "donut"

7.5" is best suited with 225-235(max).



(alutec here)


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## aero (Sep 16, 2006)

Terranismo said:


> Jalal, I have 255/55R18 tires on my wheels and they do rub slightly under full steering lock. The rears also rub when under full load in cornering.
> 
> I'm planning on going back down to 17 inch wheels and tires, once I run these bare. The unsprung weight is killing my gas consumption and making it slower to acelerate.



Absolutely too wide, DONUT shape..... 

255 is for 8.5 or 9" width rims.


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## aussietrail (Sep 24, 2004)

aero said:


> Bro, the tyres width is abit too wide. 245 or 255 with 7.5" rims will make "donut" shape (the tyres are abit out compare to the rims). Which is abit wasted in performance wise. The tyres wont seat perfectly. For performance tyre (especially low profile tyres), better avoid the "donut"
> 
> 7.5" is best suited with 225-235(max).
> 
> ...


Hi alutec and nice to see you on this forum 

I went with 245/45R18 and they're the perfect fit, no donuts or muffins, they sit perfectly on the 7.5" rim and look very straight on the sidewalls. Performance-wise, I am very happy with them, handling has improved heaps.

235 would have fitted as well, but I thought it looked a bit thin for these alloys as I had 235s with the factory 16" rims which are 6.5" wide.


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## LEONGSTER (Apr 9, 2006)

Just be a little more cautious driving in the wet - aquaplaning!


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## aussietrail (Sep 24, 2004)

LEONGSTER said:


> Just be a little more cautious driving in the wet - aquaplaning!


Hi Eddie, I don't think this will be an issue with directional tyres that are designed to be performance on road tyres especially in the wet.


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