[swill424242]

iam looking at rims with tires one set iam looking at is a
215/45/17 and the other is 225/40 /18 will 18 inch work good for my car ?

 

[nickfjields]

More importantly you need to make sure the bolt pattern and center bore are correct. The bolt pattern needs to be a 5x110 pattern, which means 5 bolts on a 110mm circle. I wouldn't say this is a rare pattern, but its not that common.

The centerbore is the round opening in the center of the wheel, the diameter is 65.1mm. Our cars use this center hole to center the wheel on the hub. If the wheels you buy do not have the same exact centerbore there is a good chance the wheel will not be centered and all sorts of bad things will happen.

Do a search here there are tons of threads on rim and tire sizes that fit our cars, as well as what doesn't and work arounds to get certain volvo/vw wheels to fit.

 

[swill424242]

I understand what u r saying and thanks for the info But i was wonderin if i get the 18's is that to big for my car ? will i lose performane ? or can my 4cyl turbo handle 18's ?

 

[belfastcarlsson]

Funny, I am having the exact same query - I would like to upgrade my Viggen rims for 18", all same sizes as yours. Worried there wouldn't be clearance inside the arches.

Hope someone can help us both.

 

[swill424242]

Iam pretty sure there will be enogh clearnce but iam just wondering what performance that i will lose

 

[nickfjields]

Iam pretty sure there will be enogh clearnce but iam just wondering what performance that i will lose

well I suppose its pretty likely the bigger rim will be heavier, which means more of the engine torque will be used to overcome the larger inertia of the wheel, yielding slower acceleration.

 

[swill424242]

Yeah very true iam sorta leaning towards the 17's but i love the look of the 18's

 

[Harquebus]

well I suppose its pretty likely the bigger rim will be heavier, which means more of the engine torque will be used to overcome the larger inertia of the wheel, yielding slower acceleration.

It also affects your final drive ratio, gas mileage and gives you a speedometer error.

 

[belfastcarlsson]

What does it do to the ratio - cause damage?

Mileage I understand due to weight. Speedo is OK, just 2%.

Overall you would be less keen thne I take it?
Should I be worried about doing 17 to 18 on a Viggen?

 

[nickfjields]

Yeah very true iam sorta leaning towards the 17's but i love the look of the 18's

http://forums.vwvortex.com/zerothread?cmd=print&id=3794166

there's some discussion at that link about the actual effect of the added weight of the wheel. They're discussing lighter wheels but it works in reverse for the added weight.

also, as far as the final drive and speedometer, the outside diameter of the tire is what matters, not the rim size. so for example if speedometer is calibrated for a tire/rim combo with a 26" outer diameter, you can use any rim as long as the tire outer diameter is the same as stock. that being said I don't know if there is a narrow enough tire to put on an 18" wheel to maintain the stock outer diameter so it is possible that there would be some speedometer error introduced

 

[Harquebus]

^ Well stated. Generally speaking, only radical changes in tire/rim size, such as the (what's the largest commercially available "bling" rim size?) tiny low rider rims and the larger 26" SUV rims mounted on the wrong application can severely alter your cars performance, making acceleration noticeably suffer and yet increase the vehicle's top speed and vice versa if I understand correctly. Larger tires rotate slower at any given road speed versus, say, small 12" "low rider rims" assuming they were not designed for the car in question and its gearing.

Apologies for my verbosity but I'd rather much have a hands-on approach than writing about it. So, I'm off to put skateboard wheels on my 900 and see how she performs.

 

[nickfjields]

Apologies for my verbosity but I'd rather much have a hands-on approach than writing about it. So, I'm off to put skateboard wheels on my 900 and see how she performs.

could get some sweet drifts going with skateboard wheels on the rear end haha

 

[Mister Bean]

^ Well stated. Generally speaking, only radical changes in tire/rim size, such as the (what's the largest commercially available "bling" rim size?) tiny low rider rims and the larger 26" SUV rims mounted on the wrong application can severely alter your cars performance, making acceleration noticeably suffer and yet increase the vehicle's top speed and vice versa if I understand correctly.

It doesn't take a radical change in size to make pretty dramatic changes in performance. Just an in has been quite noticeable to me in the past.

Top speed will only be increased if top speed was gearing limited instead of power limited.

 

[swill424242]

Ok so it seems that everyone agrees i should stay with the 17's instead of 18's

 

[saabkid37]

18's are just fine, and in fact a 225/40/18 tire is negligably bigger than a 225/45/17 (.5 inch more sidewall).

as long as you dont get a 30 pound wheel youll be fine.

the offset is more important than center bore and bolt pattern since those can both be fixed.

if you want 17's i have a set for sale in the classifieds.

 

[1oldsaabman]

I am in the same situation.... I need new wheels for my viggen & I can't decide 17 or 18. I prefer the looks of the 18's so that the direction I am leaning to, it's just I haven't read many people using 225-40-18's on their car so I do not know if it will work.

 

[saabkid37]

I am in the same situation.... I need new wheels for my viggen & I can't decide 17 or 18. I prefer the looks of the 18's so that the direction I am leaning to, it's just I haven't read many people using 225-40-18's on their car so I do not know if it will work.

there of plenty of people who have including jameson over on tsl. he ran 225/40/18 and that was on a wheel with an offset between +35 and 40. if you dont run spacers theres a small pinch weld you have to grind, or just roll the fenders and be good to go.

 

['97 Saab SE Turbo]

Don't forget about potential pothole damage. The larger the diameter of the wheel, the smaller the tires sidewall is and the more force the tire transmits to the wheel from a hole in the road. If I was going to buy 4 new wheels, I would buy one more as a spare... Ron

 

[1oldsaabman]

Don't forget about potential pothole damage. The larger the diameter of the wheel, the smaller the tires sidewall is and the more force the tire transmits to the wheel from a hole in the road. If I was going to buy 4 new wheels, I would buy one more as a spare... Ron

Kinda true but I do not buy it ..... I had 18in wheels on my SPG for 12+yrs & I never had a problem, that was with 225-40-18 tires in Ohio pothole infested roads. My brothers 98 900SET went through a few wheels & they were only 16in wheels.

I beleive it's more about how the wheel is made & the type of material then the size of the wheel.

 

[Harquebus]

It doesn't take a radical change in size to make pretty dramatic changes in performance. Just an in has been quite noticeable to me in the past.

Top speed will only be increased if top speed was gearing limited instead of power limited.

Right. I'm only speaking of gearing here and not any limitations on power. I agree on *any* change being perceptible but not everyone is so sensitive to things like that. What does come to mind is all those dudes out there with radical (there's that word again) changes in tire and rim sizes not knowing what they've done to their performance but it's all for the sake of being and looking cool. There's also the weight factor in bigger wheels, the problem of overcoming the added inertia as has already been spoken of. Bigger does not always mean heavier so go with forged aluminum. One can have a smaller wheel that is heavier than one larger because it is a heavier (and cheaper) cast aluminum wheel.