ET38 ok?

[cobra148]

Sorry for yet another wheel question. I want to make sure the next ones fit, as my last Ebay purchase wouldn't fit the Calibra.
17" wheels, ET38 with 205/40/17 rubber. Will these be fine or should I steer clear?
Thanks

[Dan Willis]

How wide are these? ET38 is a bit low... but if the rim is no more than 7inches wide you should be more than okay.

[cobra148]

I'm pretty sure they are 7". I might give it a miss a look for something a bit more suitable.

[Stupink]

I run 215 on 17's et35 lol. they scrub over hump backed bridges etc ever so slightly at the fronts. so 205 on 38 should be ok as dan says.

[MickM]

Read this...

<a href="http://homepage.ntlworld.com/betyouaint/offset.htm" target="_blank">http://homepage.ntlworld.com/betyouaint/offset.htm</a>

Then decide...!!!

[cobra148]

<!--QuoteBegin-MickM+--><div class='quotetop'>(MickM)</div><div class='quotemain'><!--QuoteEBegin-->Read this...

<a href="http://homepage.ntlworld.com/betyouaint/offset.htm" target="_blank">http://homepage.ntlworld.com/betyouaint/offset.htm</a>

Then decide...!!!<!--QuoteEnd--></div><!--QuoteEEnd-->


I've decided. Cheers for that.

[Paul]

Mine are ET38 with 215/40 R17 tyres, and I've had no problems at all.

I certainly haven't noticed any squirming under (very) hard acceleration or braking.

In fact when I had it rolling roaded the operator was saying how a lot of modified cars with aftermarket wheels scrabble and squirm slightly on the rollers, whereas mine sat there absolute perfectly.

That said, obviously it would be better to get something nearer ET49 if you can.

[MickM]

<!--quoteo--><div class='quotetop'></div><div class='quotemain'><!--quotec-->I certainly haven't noticed any squirming under (very) hard acceleration or braking.<!--QuoteEnd--></div><!--QuoteEEnd-->There's a good reason that manufacturers stipulate a certain offset and it has less to do with aesthetics than it does handling. The physics of it is plain to see although in practice it's not always quite so obvious. During regular day to day driving you probably wouldn't notice but get your Michael Schumacher head on and start to push it the problem may become more apparent. Even then it's only in certain circumstances, ie. inconsistent road surface. Again the more power you have or the harder you brake the more pronounced the effect will be. I supose it's all about circumstances and the way you drive...

Some people run a locked box on their 4x4s despite the design notes which clearly explain the reason for the "disengageable" system employed on the Calibra, ie. the instability of running a locked system under braking. How many people have had an accident as a result of running a locked box..? None that I know of but the fact is that under certain conditions, when all things are not equal, a locked box may cause the car to spin. Same sort of thing really..!!?

I just don't see the point is spending money on lowering and stiffening a car, fitting powerflex bushes and low profile "top of the range" tyres to then have alloys with the incorrect offset and throw away all the good work. Then again, I suppose if you just want the car to look nice then it might not be a big deal to you. If handling and stability are your priority then it's a different matter...

[Paul]

Mick,

I completely agree with what you're saying in theory.

When I bought my alloys ET38 was what was recommended by the Garage/Wolfrace at the time. (Although I believe they now do an ET42 in the same wheel)

All I am saying is that I personally haven't noticed any difference from the standard wheels.
I do drive the car hard, and push it's limits (260Bhp, 289lb ft) and often accelerate at full throttle out of nice corners in second gear etc.
My braking isn't exactly gentle either. (Not that the standard brakes are up to much anyway)

On the other hand, my suspension is completely standard, so this may dampen some of the effects I would otherwise feel.

I'd obviously recommend that people buy near ET49 if possible, but I personally can't feel enough of a problem with my ET38 to warrant getting a new set of alloys.

[Dan Willis]

<!--QuoteBegin-MickM+--><div class='quotetop'>(MickM)</div><div class='quotemain'><!--QuoteEBegin-->Some people run a locked box on their 4x4s despite the design notes which clearly explain the reason for the "disengageable" system employed on the Calibra, ie. the instability of running a locked system under braking. How many people have had an accident as a result of running a locked box..? None that I know of but the fact is that under certain conditions, when all things are not equal, a locked box may cause the car to spin. Same sort of thing really..!!?<!--QuoteEnd--></div><!--QuoteEEnd-->

I believe one person has... or at least, the blame was on the box.

I cannot remember the details but it was something to do with the car not stopping on a roundabout and spinning in to something...

I have an idea though [img]/smile.gif[/img]

[cobra148]

I had a problem with my old Corsa when it had ET40 wheels on it. I tramlined like a b***h, and keeping a straight line on the inside lane of the motorway was hard work.
I'm a novice with the Calibra, hence the question about the offset, I want to get a set of wheels that will fit fine and run with no problems at all.
I'm looking at a set of OZ Hydra's now, these are ET45 offset so I'm hoping they will be problem free.

[MickM]

I would have thought that ET45s were close enough. As Paul has said, he didn't even notice the difference running ET38s. Being an engineer I can get paranoid about these things but in my experience it just didn't feel right. It's a shame cause I really love the OZ Polaris wheels I had and thought they complemented the Calibra lines perfectly...

<a href="http://homepage.ntlworld.com/betyouaint/Before.jpg" target="_blank">http://homepage.ntlworld.com/betyouaint/Before.jpg</a>

I'd love to find some with the correct offset but they probbaly never did them... [img]/sad.gif[/img]

[Animal]

Can't you get them machined a bit closer?

[projectx]

<!--QuoteBegin-Stupink+--><div class='quotetop'>(Stupink)</div><div class='quotemain'><!--QuoteEBegin-->I run 215 on 17's et35 lol. they scrub over hump backed bridges etc ever so slightly at the fronts. so 205 on 38 should be ok as dan says.<!--QuoteEnd--></div><!--QuoteEEnd-->

Ditto...et35's on 215x40x17, and yeah it does scrub a bit on the top of the arch. But you should be OK, as others have said, so long as your wheels aren't too wide...Oh, mine are 8j's as well LOL

[MickM]

When I was running ET38 on a lowered car even corninging caused the tyres to scrub the arch.

<!--quoteo--><div class='quotetop'></div><div class='quotemain'><!--quotec-->Can't you get them machined a bit closer?<!--QuoteEnd--></div><!--QuoteEEnd-->I suspect you could but I think it was Kingsley who posted a while back concerning this suggesting it couldn't or rather shouldn't be done.

I would have thought that all the wheels for a given style would be cast the same (for a given radius - 16", 17", 18", etc.) and then drilled and machined back to suit stud patterns and offset. This would mean that an ET48 could be machined from an ET38..? The problem arises though if a wheel was never designed to be machined down to fit ET48. You could end up with too little material and seriously compromise the structural integrity of the wheel. Maybe this is what Kingsley was talking about...?