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[Big_Al]

hi guys & gals
                        I have been looking at some new 17" alloys for the Omega.  Want to fit new tyres as well & was discussing thois with a local alloy wheel/tyre supplier.

I mentioned that my opinion of 235 45  17 tyres on 17"  rims on the Omega makes the wheelarch/tyre gap seem a bit excessive.

The tyre guy suggested that 235 50  17,s    would look better.

He seemed to think that it would decrease this gap by 10 - 12mm & make the car look like it is sitting slightly lower.

He also mentioned that the speedo reading would be slightly incorrect but by a minimal amount.

Any thoughts on this idea.

[cem_devecioglu]

not sure tech 2 can arrange on that size but his suggestion is logical imo.. if your roads are not perfect those tires will protect your wheels and will be more comfy.. but 235 width will make the steering stiffer and increase the fuel consumption as you can guess..

[Big_Al]

not sure tech 2 can arrange on that size but his suggestion is logical imo.. if your roads are not perfect those tires will protect your wheels and will be more comfy.. but 235 width will make the steering stiffer and increase the fuel consumption as you can guess..

width
I'm sure that 235 tyre width is factory fitted on facelift Elites as mine is.   235  x 45 x 17

Might be wrong though

[aaronjb]

not sure tech 2 can arrange on that size but his suggestion is logical imo.. if your roads are not perfect those tires will protect your wheels and will be more comfy.. but 235 width will make the steering stiffer and increase the fuel consumption as you can guess..

width
I'm sure that 235 tyre width is factory fitted on facelift Elites as mine is.   235  x 45 x 17

Might be wrong though

It is AFAIK (ditto on mine)

[cem_devecioglu]

I dont care what factories fit

I use 215  55 16.. good price even in good brands .. and adequate imo..

[Big_Al]

I dont care what factories fit

I use 215  55 16.. good price even in good brands .. and adequate imo..

Might struggle to get them on my 17" rims  

[cem_devecioglu]

I dont care what factories fit

I use 215  55 16.. good price even in good brands .. and adequate imo..

Might struggle to get them on my 17" rims  

for the price of good brand 17 tires you can buy a set of wheels and good tires.. erm .. might be necessary to add some

[2woody]

and this is a tyre fitter....?

In short :-

yes, the speedo will be wrong - almost 4%, which is quite a large amount.

yes, the car will handle poorly - the suspension geometry is designed around the hub being 11.7 inches from the road. You're moving this up by half an inch, which is a massive amount, affecting handling, grip and stability under both cornering and braking.

[51M0N]

and this is a tyre fitter....?

In short :-

yes, the speedo will be wrong - almost 4%, which is quite a large amount.

yes, the car will handle poorly - the suspension geometry is designed around the hub being 11.7 inches from the road. You're moving this up by half an inch, which is a massive amount, affecting handling, grip and stability under both cornering and braking.

Bizzare as this may sound my speedo is only 1/2mph out from a gps reading. which is about right for a Vaux anyway on standard sized wheels.

[feeutfo]

Also the bigger wheel diameter will have the effect of raising the gearing, so the car won't be as quick. Although might save a bit of fuel.

[2woody]

the rules for speedo accuracy take account of the worst-case - which is I guess the smallest tyre diameter (after the tread has worn), plus the softest rubber, etc. So you tend to get between about 8% and 1% error

[51M0N]

Also the bigger wheel diameter will have the effect of raising the gearing, so the car won't be as quick. Although might save a bit of fuel.

Still quick enough 

[feeutfo]

Also the bigger wheel diameter will have the effect of raising the gearing, so the car won't be as quick. Although might save a bit of fuel.

Still quick enough 

Er, no! actually. 

[cem_devecioglu]

the rules for speedo accuracy take account of the worst-case - which is I guess the smallest tyre diameter (after the tread has worn), plus the softest rubber, etc. So you tend to get between about 8% and 1% error

assume, speedo is out by %10.. what happens .. you know speedo reading is fake , so arrange your speed accordingly..

here there are many road radars (without police) (and I'm sure there also exist) showing your speed that you can compare yours without having gps..

[51M0N]

Also the bigger wheel diameter will have the effect of raising the gearing, so the car won't be as quick. Although might save a bit of fuel.

Still quick enough 

Er, no! actually. 

Maybe yours isn't but the 40+ bhp I have over standard will make up for the huge tyres.