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Did I Purchase A Wrong Size Tyre For X Wheels?


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Hi guys,

Just back from tyre shop to put on new x pacakge 18inch wheels in my is250.

The wheels looking great but for some reason something looks odd for the front one. The tryre size seems not wide enough for the wheels so the lip is sticking out (hence not much wheel protection too). Is it possible that the tyre is not mounted properly? It looks a little ugly to be honest :(

I confirm many times from many online sources and dealer that the front tyre size is 225/40/18 for 18/8 wheel size. Which is the tyre that I bought, but I'm wondering it can look like that if it's OEM recomended size?

Tyre is Kumho KU22.

See pic for better explanation of the situation.

Any toughts? any x package owners experience this too?

post-7119-0-40879000-1390977256_thumb.jp

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It just depends on the tyre brand. my previous tyres looked like that but I've got pirelli's atm and it is pretty meaty next to the lip. no need to worry

:) Thanks guys! made me feel better... I guess I won't need to worry then since you all have same ones. For the next tyre change will 235/40 fit without rubbing?

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Hi guys,

Just back from tyre shop to put on new x pacakge 18inch wheels in my is250.

The wheels looking great but for some reason something looks odd for the front one. The tryre size seems not wide enough for the wheels so the lip is sticking out (hence not much wheel protection too). Is it possible that the tyre is not mounted properly? It looks a little ugly to be honest :(

I confirm many times from many online sources and dealer that the front tyre size is 225/40/18 for 18/8 wheel size. Which is the tyre that I bought, but I'm wondering it can look like that if it's OEM recomended size?

Tyre is Kumho KU22.

See pic for better explanation of the situation.

Any toughts? any x package owners experience this too?

I am starting to worry now because I am getting Kuhmo KU22 225/40/18 x 8" FRONT and the reason is because they have a rim protection (the existing Kuhmo KU31 225/40/18 x 8" have no rim protection) so do you think I should now choose Kuhmo KU22 235/40/18 x 8". The Pirelli P1 is the best for rim protection but the cost is much more.

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Hi Ricky,

I check few forums and 235/40/18 will not rub so its safe to go, and as for rim protection and better look i think it's the way to go?

Altough 225 is ok, but i really dislike the look... Looks like a smaller size in front :(

I'm going back to to tyre shop tomorrow for a test fit with 235/40. Hopefully the want to trade with my 225 since its only 1 day old..

I'll take a pic once its done

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Hi Ricky,

I check few forums and 235/40/18 will not rub so its safe to go, and as for rim protection and better look i think it's the way to go?

Altough 225 is ok, but i really dislike the look... Looks like a smaller size in front :(

I'm going back to to tyre shop tomorrow for a test fit with 235/40. Hopefully the want to trade with my 225 since its only 1 day old..

I'll take a pic once its done

The 225/40/18 x 8" is correct fitment, so the KU22 has a rim protector but doesn't show on you rim, even my KU31 without rim protectors protude slightly more from the rim, just make sure you haven't an 8.5" rim on the front. What is the point of having the rims protectors then? I haves attached a photo of my wheel with the KU31 (it is the back but the front is the same).post-4790-0-74696700-1390995518_thumb.jp

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Yeah my rims protectors doesn't show up at all. Infact front rims stick out for about 0.5 - 0.75 cms which lead me to believe that maybe the tyre shop put the 225 on 8,5 back wheels. Its possible that they did it wrong.

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No that is just the way they look .... I had Bridgestones on mine (factory fitted) and didn't like the look at all ... the lip is rim protector. The size is correct 225/40R18 .... rear is 255/40 on half inch wider rim.

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For my last service, Lexus loaned me a new IS250, tyres on the front and back were 225/40/R18 Yokahamas I think but the rim protector was a ridge that protruded at least 8mm from the rim, so if you lightly brushed a kerb that would protect the rim, my friend has a new Senator with Continental tyres on and they have arum protector on as well. Lexus of Perth have recommended that the Pirelli P1 have the best rim protector but the rears only come in 245/40/R18 not 255/40/R18.

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I can understand why u didnt loke the look :( so am I. My lip is totally exposed, and i worry even a llittle pothole will ruin the rim

I wonder why 225 is the oem reccomended tyre size not 235.

I think it is to do with the smooth steering, the steering may be slightly harder with the 235. A friend had fitted 8.5" non standard rims on the front and had rubbing issues together with heavy steering, the tyre people say to keep the tyre 225/40/R18 x 8" on the front but able to fit 9.5" rims on the back with suitable tyres to fit the rim.

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I just back from tyre shop. Re-fitted front with Kumho KU22 235/40/18 and it's perfect! The tyre protruded a little hence enough rims protection. It does look much better too.

No rub at all - and didn't notice any difference on the weight of the steering (it probably a tiny difference almost unnoticeable).

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I just back from tyre shop. Re-fitted front with Kumho KU22 235/40/18 and it's perfect! The tyre protruded a little hence enough rims protection. It does look much better too.

No rub at all - and didn't notice any difference on the weight of the steering (it probably a tiny difference almost unnoticeable).

Hey, that is great, thanks for that it will make me definitely choose the 235 over the 225

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  • 2 weeks later...

Going to 235/40 over 225/40 wouldn't this increase the rolling diameter of the tyre which in turn puts your speedo reading out?che_ryan,what did your tyre guy say about this?

Hi Tony...The guys at the tyre shop said it's ok as the aspect ration sill the same (235/40/18).

I've driven the new tyre for about 2 weeks now. and it seems ok. I mean it's hard to notice if the speedo off, but when I do 100km/h on eastern freeway looks like my speed is the same like any other car around me hahaha. Preety lame method of testing huh? :)

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Going to 235/40 over 225/40 wouldn't this increase the rolling diameter of the tyre which in turn puts your speedo reading out?che_ryan,what did your tyre guy say about this?

Hi Tony...The guys at the tyre shop said it's ok as the aspect ration sill the same (235/40/18).

I've driven the new tyre for about 2 weeks now. and it seems ok. I mean it's hard to notice if the speedo off, but when I do 100km/h on eastern freeway looks like my speed is the same like any other car around me hahaha. Preety lame method of testing huh? :)

Hi Tony, The aspect ratio is still the same so it will not affect the speedo. I am definitely going to get these - can you show photo of the sidewall with the rim, I would like to see how much the tyre sticks out from the rim. Kuhmo has sent me pictures of the KU22 tyre but it doesn't show anything because it is not on a rim.

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Going to 235/40 over 225/40 wouldn't this increase the rolling diameter of the tyre which in turn puts your speedo reading out?che_ryan,what did your tyre guy say about this?

Hi Tony...The guys at the tyre shop said it's ok as the aspect ration sill the same (235/40/18).

I've driven the new tyre for about 2 weeks now. and it seems ok. I mean it's hard to notice if the speedo off, but when I do 100km/h on eastern freeway looks like my speed is the same like any other car around me hahaha. Preety lame method of testing huh? :)

Hi Tony, The aspect ratio is still the same so it will not affect the speedo. I am definitely going to get these - can you show photo of the sidewall with the rim, I would like to see how much the tyre sticks out from the rim. Kuhmo has sent me pictures of the KU22 tyre but it doesn't show anything because it is not on a rim.

It's not just the aspect ratio which affects the speedo, it's the Rolling diameter.

In your case 225/40/R18 is 637.2mm

and the new one 235/40/R18 is 645.2mm which will result in a -1.26% error.

If the seepdo is calibrated correctly when it's showing 100/kph the car will be doing only 98.74 kph; a slight under-read...

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Going to 235/40 over 225/40 wouldn't this increase the rolling diameter of the tyre which in turn puts your speedo reading out?che_ryan,what did your tyre guy say about this?

Hi Tony...The guys at the tyre shop said it's ok as the aspect ration sill the same (235/40/18).

I've driven the new tyre for about 2 weeks now. and it seems ok. I mean it's hard to notice if the speedo off, but when I do 100km/h on eastern freeway looks like my speed is the same like any other car around me hahaha. Preety lame method of testing huh? :)

Hi Tony, The aspect ratio is still the same so it will not affect the speedo. I am definitely going to get these - can you show photo of the sidewall with the rim, I would like to see how much the tyre sticks out from the rim. Kuhmo has sent me pictures of the KU22 tyre but it doesn't show anything because it is not on a rim.

It's not just the aspect ratio which affects the speedo, it's the Rolling diameter.

In your case 225/40/R18 is 637.2mm

and the new one 235/40/R18 is 645.2mm which will result in a -1.26% error.

If the seepdo is calibrated correctly when it's showing 100/kph the car will be doing only 98.74 kph; a slight under-read...

Going to 235/40 over 225/40 wouldn't this increase the rolling diameter of the tyre which in turn puts your speedo reading out?che_ryan,what did your tyre guy say about this?

Hi Tony...The guys at the tyre shop said it's ok as the aspect ration sill the same (235/40/18).

I've driven the new tyre for about 2 weeks now. and it seems ok. I mean it's hard to notice if the speedo off, but when I do 100km/h on eastern freeway looks like my speed is the same like any other car around me hahaha. Preety lame method of testing huh? :)

Hi Tony, The aspect ratio is still the same so it will not affect the speedo. I am definitely going to get these - can you show photo of the sidewall with the rim, I would like to see how much the tyre sticks out from the rim. Kuhmo has sent me pictures of the KU22 tyre but it doesn't show anything because it is not on a rim.

It's not just the aspect ratio which affects the speedo, it's the Rolling diameter.

In your case 225/40/R18 is 637.2mm

and the new one 235/40/R18 is 645.2mm which will result in a -1.26% error.

If the seepdo is calibrated correctly when it's showing 100/kph the car will be doing only 98.74 kph; a slight under-read...

I have been told that some car manufacturers under calibrate the speedo to show a percentage less, they mus then adjust the SatNav as well. I guess this is to avoid any class action to them in case you are picked up for speeding and claim the speedo was in error.

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Yes, i think every car manufacturer does this. A rough test is to drive under one of the Advisory speed detection lanes on the highways - think Hume and geelong ones have them.

Driven several different cars on these and at 100kph they've always under-read usually between 92 to 96kph.

From what I've heard in Europe the margin is between 10-15%, but in our Nanny state of Vic it's widely assumed to be around 3%.

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