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[cem_devecioglu]

OK guys I really don't want you arguing about it. I guess you both are right on different things.

225/50/17 yes are big for my car according to tire size calculator. but I will have to agree with Taxi Al on the 225/45/17 as they have almost the same diameter as the original one(195/65/15)... take a look on result from www.miata.net website:



and yes I am using spacer for my 18" rims but not sure if 12 or 15 mm.

my current rims are aftermarket made and one of them I doubt to be bent so the car is not stable when I go over 90km/ph.
whats more I am looking for more comfort ride in my new rims using higher tires(45 or 50) I am having a bad experience with the current ones especially when I go over a road bump. but what concerns me the most is the car acceleration, I tried a 2.0 omega and it's a way better than my 2.5 V6.

I would go for a 16" rims but I couldn't find any around here not even the 15".

And please no need to argue about it, as Cem said it's was just a simple help question.

Many thanks!

225/45-17 was told by me   


 I wont go in the long details but if you use a different circumference tire, your speedo will be out (can be corrected via tech 2 with a cost)
and your gearing ratios will be changed effecting acceleration..

[05omegav6]

Apology accepted Cem, as 225/45/17 isn't an Omega tyre size

[Rifai]

I wasn't arguing

Anyways, my Irmscher Stila 18" wheels have an offset of ET33, but Irmscher Sportstars have an offset of ET30.
Both are Omega fitments, so whichever spacer you can find more easily will be fine

Note, with some tyres you can get away with an offset of ET38 with 8J 18 wheels, but they can rub on the front struts, so aren't recommended...

You will find that 225/55/16 and 245/40/18 are the same rolling radius. 235/45/17 and 235/40/18 are almost the same rolling radius...

Incidentally details of the official factory tyre sizes for the facelift can be found on pages 227 and 228 of the Owners manual, here...

http://www.omegaowners.com/forum/index.php?topic=90477.0

The official 18" tyre sizes come from Irmschers certificate of conformity supplied with the wheels when new

Factory wheel/tyre sizes depend on engine size and spec, but all Omega Bs from '94-'03 have 195/65/15 spare wheels as standard.

Facelift cars had the following...

Four cylinder, including diesel...
195/65/15
205/65/15
225/55/16
235/45/17

All V6s...
205/65/15
225/55/16
235/45/17

Pre facelift cars had the following...

All four cylinder...
195/65/15
205/65/15
225/55/16

All v6...
205/65/15
225/55/16
235/45/17 MV6 only, '97-'99.

Hopefully that answers your wheel/tyre questions

the manual doesn't include my engine type X25XE, so i am not really sure about it. 235/45/17 or 225/45/17

based no google search I found out that the new tires should have the same diameter as the original ones 195/65/15 and that leads me to 225/45/17 which have identical diameter, radius and circumference. also based on my information a 225 wide tires should give a better acceleration & smoother steering(correct me if I am wrong).

I really don't want to spend 800 euros on rims and new tires and get the same result as my current 18" wheels 

225/45-17 was told by me   


 I wont go in the long details but if you use a different circumference tire, your speedo will be out (can be corrected via tech 2 with a cost)
and your gearing ratios will be changed effecting acceleration..

Oh my apologies, sorry  .

but I really didn't get the following part:

your speedo will be out (can be corrected via tech 2 with a cost)

[05omegav6]

You can ignore that about the speedo

The exact wheel/tyre combo in the manual depends on spec. The manual in the link is the facelift one, but I have listed the prefacelift ones too.
If you run all those tyre sizes listed through the convertor on miata.net you will see whatthe minimal differences of the rolling radii are. Anything below 2% can be ignored as the speedo is only accurate to 10%.

Being a V6 Your car would have left the factory with 205/65/15 tyres fitted, so use that size as your bench mark in the conversion calculator

[cem_devecioglu]

Apology accepted Cem, as 225/45/17 isn't an Omega tyre size

it has the same circumference with 195/65-15


but 235 45 17 is bigger apparently

[Rifai]

Apology accepted Cem, as 225/45/17 isn't an Omega tyre size

it has the same circumference with 195/65-15


but 235 45 17 is bigger apparently

Thanks man 

Apology accepted Cem, as 225/45/17 isn't an Omega tyre size

it has the same circumference with 195/65-15


but 235 45 17 is bigger apparently

 

[Rifai]

You can ignore that about the speedo

The exact wheel/tyre combo in the manual depends on spec. The manual in the link is the facelift one, but I have listed the prefacelift ones too.
If you run all those tyre sizes listed through the convertor on miata.net you will see whatthe minimal differences of the rolling radii are. Anything below 2% can be ignored as the speedo is only accurate to 10%.

Being a V6 Your car would have left the factory with 205/65/15 tyres fitted, so use that size as your bench mark in the conversion calculator

you are absolutely right. thank you so much!! I went back to car manual and yes it was 205/65/15 the 195/65/15 was the spare wheel size.

Now I guess I need  215/50/17 tires and it will be OK.

Thank you All for your help, much appreciated 

[TheBoy]

On a 7.5J, 225 may be a shade narrow, 215 will start to look a bit shite. If tyre costs need you to go narrower, consider getting the right rims for that size.

UK insurance companies can be a bit touchy over tyre sizes not approved by the manufacturer, so you may need to declare non standard sizes (usually doesn't bump the premium too much, esp if its an optional extra size_

[chrisgixer]

Hello,

I have Opel Omega B 2.5 CD 1997 X25XE / 170hp

can any one please tell me the original wheel size that comes on it? I know it's 15" but I need to know the wheel width and ET.

the car came with 7j 18" ET45 aftermarket rings with spacer, I believe it's not the right the size for my car and it's affecting the car performance especially when taking off.

I know 7j 16" will fit OK on my car but I couldn't find that size in my country.

will a 17" 7.5j ET39 (the omega 2003 rims) fit on my car? will there be any issues especially with the wheel width 7.5j ?

I appreciate your advice on the matter and sharing your personal experience.

Yes they will fit fine.

Re width, the only 235 45 17 tyre I have had a problem with was a Bridgestone potenza 010 with MASSIVE rim protection to the point that they physically will not go on the hub for fouling the shock. With rim protection that much over size those tyres would have potential fitment issues no matter what vehicle they where fitted to. They are not a nice tyre and outdated so don't buy those and you'll be fine.

Omega chassis components and body/wheel arch dimensions are the same across the range. So any oe wheel size will fit any omega.

[cem_devecioglu]

You can ignore that about the speedo

The exact wheel/tyre combo in the manual depends on spec. The manual in the link is the facelift one, but I have listed the prefacelift ones too.
If you run all those tyre sizes listed through the convertor on miata.net you will see whatthe minimal differences of the rolling radii are. Anything below 2% can be ignored as the speedo is only accurate to 10%.

Being a V6 Your car would have left the factory with 205/65/15 tyres fitted, so use that size as your bench mark in the conversion calculator

you are absolutely right. thank you so much!! I went back to car manual and yes it was 205/65/15 the 195/65/15 was the spare wheel size.

Now I guess I need  215/50/17 tires and it will be OK.

Thank you All for your help, much appreciated 

for your information , opel use 195 size on that year .. for GLS and CD


and also

[05omegav6]

Wikipedia or Google?

[05omegav6]

Also, depending on the market, tyre sizes are often on the chassis stickers

[cem_devecioglu]

Wikipedia or Google?

cant you see the chart

[cem_devecioglu]

but obviously its not 235 45 17

[05omegav6]

Third from bottom of the 2.5 list, but table is clearly from your imagination rather than your owners manual