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Discussion Starter #1
I currently run 225/40/18 and need new tires (today since the sale ends today) and want to step up my sidewall height a tad.

People are running 225/45/18 without issues, right? I'm stock, not lowered (unfortunately).
 

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I don't know for sure about inner clearances but it shouldn't be an issue.
Your speedo will read slower than it actually is (3.5% faster per rotation) and your acceleration will take a small hit.

Try this:
http://www.rimsntires.com/specs.jsp

I would not do it but it should be okay if all you're concerned with is wheel well clearances.
 

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Discussion Starter #4
I don't know for sure about inner clearances but it shouldn't be an issue.
Your speedo will read slower than it actually is (3.5% faster per rotation) and your acceleration will take a small hit.

Try this:
http://www.rimsntires.com/specs.jsp

I would not do it but it should be okay if all you're concerned with is wheel well clearances.
Hey TG - thanks for the info. I ran all the specs, and don't mind the 3.5% difference. Some Volvos came stock with 215/45/18 so a minor bump to 225 shouldn't be much of an issue...

Just curious, why wouldn't you do it?
 

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Just curious, why wouldn't you do it?
Oh, mostly because of the speedo error. Speed reading isn't all that accurate to start with. I wouldn't want to add to the error. I like to monitor my mileage and gas consumption. Overall I don't see the benefit of up-scaling the side wall by so little in comparison to the disadvantages. Perhaps if you drive a lot on flat and on highways you could see your mpg increase.If you do a lot of city driving you could get the reverse effect...

I'm also not that crazy about reduction in acceleration even if it is by a little bit. I spent too much money on the car already in performance mods :p
Aside from obvious weight reduction there is a reason why Minis and small VW are quicker. Tiny tires :)

FYI: 215 tires is much less of an error and much more in tune with Volvo tire+wheel range for our cars. OEM often comes with 16" (15" in Europe very often) and 215/40/18 is just about the same diameter as 205/55/16. So 215 would actually be preferable to start with.
 

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Discussion Starter #7
Overall I don't see the benefit of up-scaling the side wall by so little in comparison to the disadvantages.
Benefit #1 = Greater sidewall = better protection against a bent rim on these crappy VT roads

Benefit #2 = Less fender gap! (By far the best benefit for a stock 4x4 gap like mine!) :p

I appreciate your input! For a daily driver like me, I think the extra height will work well. No performance mods here, just wheels and stickers! :D
 

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The speedo error isn't worth considering...

Example:

C30 uses the same wheel/tire ratings as the V50/S40. A 225/40 R18 doesn't require a speedo update, where as a 215/45 R18 does. With 225/40 R18 your speedo is near to spot on than if you have the speedo update. I had my car on 215/45 R18 and the update (from dealer). Result: at 100 km/h (speedo) I was going something like 95 km/h in person. As I changed my rims to winters, I had the speedo patch removed. As I then went back to 18" I didn't have the update. My speedo read exactly 100 km/h and the GPS measurement was spot on 100 km/h.

With my 19"s I have 225/35 R19. My speedo is still spot on. All fine. The larger the wheel diameter, the closer you get to a perfectly calibrated speedo. If you had 215/45 R18 before (from dealer), then it will read the same as with any 17" or so.

Thrus, diameters aren't all one side. If the wheel is say 1 cm larger in diameter, it means you have 5 mm more ground clearance and 5 mm less fender gap. Thrus, just because the tyres are written down as "225/40 R18" it doesn't mean they will be exactly those measurements. Tolerances in every company make the tyres larger/narrower. My 225s are actually 231s. So 6 mm wider than claimed. My 215s in 18" were actually only 213s. And my 195/65 R15s are 200s. There are tolerances etc. So a calculated figure is only theory! Practical it can be more or less.
 

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I added this to my previous quote too...

Perhaps if you drive a lot on flat and on highways you could see your mpg increase.If you do a lot of city driving you could get the reverse effect...
All this is very personal though and not that big of a deal I agree. Just me... I can appreciate your take on the situation :D
FYI, since I've lowered my car I got two flat tires on two different almost new set of tires. I never bent a rim and the roads are a mess too here.
Why I got flats? . . . from a screw and a nail... bigger side wall would not have helped me :(
 

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I added this to my previous quote too...



All this is very personal though and not that big of a deal I agree. Just me... I can appreciate your take on the situation :D
FYI, since I've lowered my car I got two flat tires on two different almost new set of tires. I never bent a rim and the roads are a mess too here.
Why I got flats? . . . from a screw and a nail... bigger side wall would not have helped me :/
No but a bigger side wall will prevent damage to your rims if you carry on driving (for example no possibility to stop as no hard shoulder/emergency lane etc.) ;)
 

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Discussion Starter #11
Oh yeah, TG, I read about your flat tire headaches! I definitely felt for you there.

I do mostly highway driving, so the taller tire would help lower the revs (even minimally) so I might gain some mpgs. My desire for greater sidewall comes more from a comfort level as the 40 series rides so harsh when coupled with the awd stiff suspension, so any added shock absorption through the tire helps.

Again, thanks for all your advice! I think I will pull the trigger as I can get a $100 rebate today! Oh, and if anyone needs tires, I HIGHLY recommend www.discounttiredirect.com - great prices and service, and shipping is included in the prices!
 

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Though I mostly agree with you I can't say that the market wheel options Volvo plans to offer to their different customers across markets are going to be the same across models. So Possibly C30/S40/V50 even C70 have the same factory speedo calibration but possibly they are not... based on what configuration they think they will sale the car most. A lot of the earlier S40 were sold in 2.4i with 16". C30s came later with most often with 17" and a more likelihood of an upgrade to 18". You might still be quite correct but just a thought...


The speedo error isn't worth considering...

Example:

C30 uses the same wheel/tire ratings as the V50/S40. A 225/40 R18 doesn't require a speedo update, where as a 215/45 R18 does. With 225/40 R18 your speedo is near to spot on than if you have the speedo update. I had my car on 215/45 R18 and the update (from dealer). Result: at 100 km/h (speedo) I was going something like 95 km/h in person. As I changed my rims to winters, I had the speedo patch removed. As I then went back to 18" I didn't have the update. My speedo read exactly 100 km/h and the GPS measurement was spot on 100 km/h.

With my 19"s I have 225/35 R19. My speedo is still spot on. All fine. The larger the wheel diameter, the closer you get to a perfectly calibrated speedo. If you had 215/45 R18 before (from dealer), then it will read the same as with any 17" or so.

Thrus, diameters aren't all one side. If the wheel is say 1 cm larger in diameter, it means you have 5 mm more ground clearance and 5 mm less fender gap. Thrus, just because the tyres are written down as "225/40 R18" it doesn't mean they will be exactly those measurements. Tolerances in every company make the tyres larger/narrower. My 225s are actually 231s. So 6 mm wider than claimed. My 215s in 18" were actually only 213s. And my 195/65 R15s are 200s. There are tolerances etc. So a calculated figure is only theory! Practical it can be more or less.
 

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No but a bigger side wall will prevent damage to your rims if you carry on driving (for example no possibility to stop as no hard shoulder/emergency lane etc.) ;)
Hey hey... for that it depends also on the tires too. I just had first hand experience last week. I drove unknowingly 8miles (13km) on a flat tires with my Michelins. Mixed highways, cobble stones, and uneven city roads. Rims did not have a single blemish. But yeah I did not need to go over hard shoulder in an emergency stop. I hear you!


Oh yeah, TG, I read about your flat tire headaches! I definitely felt for you there.

Again, thanks for all your advice! I think I will pull the trigger as I can get a $100 rebate today! Oh, and if anyone needs tires, I HIGHLY recommend www.discounttiredirect.com - great prices and service, and shipping is included in the prices!
:thumbup:
thx and no problem...
 

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Though I mostly agree with you I can't say that the market wheel options Volvo plans to offer to their different customers across markets are going to be the same across models. So Possibly C30/S40/V50 even C70 have the same factory speedo calibration but possibly they are not... based on what configuration they think they will sale the car most. A lot of the earlier S40 were sold in 2.4i with 16". C30s came later with most often with 17" and a more likelihood of an upgrade to 18". You might still be quite correct but just a thought...
Not "might still be correct" it IS correct. Most C30s here are delivered on 195/65 R15! Only a few bigger engines get the 16"s.

Volvo offers only one software patch for the speedo and it is added, that this only refers to tyres in 215/45 R18. 225/40 R18 have a smaller circumference than the 215/45 R18 which requires the speedo adjustment. The speedos between C30/S70/S40 and V50 until 2007 and after are the same (04-07 and 08-13). You can take it from one and fit it in the other.

Here detailed by Volvo:
Midir (uses factory 215/45 R18) http://accessories.volvocars.com/Ac...-)/2005/all/all/L.H.D/ShowDocument/VCC-449490

+ Application2
Part. No.
30660456
and

2 Ordered through separate procedures and downloaded using VIDA.
At the same time a spider rim:

http://accessories.volvocars.com/Ac...-)/2005/all/all/L.H.D/ShowDocument/VCC-449586

Both are listed under a 2005 V50 (which is the same chassis wise as an S40 or C30 or C70).

And some calculations:

195/65 R15
Diameter: 63.5 cm
Circumference: 192.9 cm

205/55 R16
Diameter: 63.2 cm
Circumference: 192.1 cm

205/50 R17
Diameter: 63.7 cm
Circumference: 193.6 cm

215/45 R18
Diameter: 65.1 cm
Circumference: 197.8 cm

225/40 R18
Diameter: 63.7 cm
Circumference: 193.7 cm

225/35 R19
Diameter: 64 cm
Circumference: 194.6 cm

As you can see, my 225/35 R19 are larger than the 225/40 R18 but still smaller in total size than the 215/45 R18. Volvo only says "215/45 R18 with speedo update/patch". Nothing else.
 

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Yes...

but you missed my point. I was just saying it is software based. What they offer in terms of wheels and tire options have nothing to do with how they calibrate the speedometer in factory. They can change that from year to year if they want to (I'm not saying they do). Vida will tell you what you can use. Does it tell you what size is optimum for the speedometer calibration for a set model? Does it tell you if Volvo adapt that calibration based on markets, model, year, they sale the cars to?

I'm sure they design enough sloppiness to allow them not to have to worry too much about that but who knows... I don't.

I was also not comparing 215/45/18 but 215/40/18. They use 45 and the 215 because it is Volvo safer or because they pair it with some specific tire brands. Hens the software update needed...
 

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Speedos are all the same... Even the software is the same... The only difference is found on the dials themselves and the revcounter on diesels...

You're missing my point at the same time. I understood what you meant. I not long ago sold a set of 4 Atreus rims in 215/45 R18. Before I sold them, I asked my dealership if certain models can drive them and which can't. Thrus finding out, if an update is required throughout the entire model range or only on the C30. Answer from Volvo (Sweden!) was, that it is all the same. All P1s need an update for only 215/45 R18s. Any other size (if smaller diameter) doesn't as they are loosely calibrated.

Have you not yet used GPS to measure the difference between your speedo and what you are properly driving? If no: do so. You'll see how much Volvos settings differ from that shown. And that is the same on all cars...
 

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You're missing my point at the same time. I understood what you meant. I not long ago sold a set of 4 Atreus rims in 215/45 R18. Before I sold them, I asked my dealership if certain models can drive them and which can't. Thrus finding out, if an update is required throughout the entire model range or only on the C30. Answer from Volvo (Sweden!) was, that it is all the same. All P1s need an update for only 215/45 R18s. Any other size (if smaller diameter) doesn't as they are loosely calibrated.
I'll take your word for it ;)

Have you not yet used GPS to measure the difference between your speedo and what you are properly driving? If no: do so. You'll see how much Volvos settings differ from that shown. And that is the same on all cars...
No I never did. I'm not sure why :p
I'll do so before year's end just to compare between my summer 225/40/18 and winter 205/55/16 . . . (it won't be the worse case scenario though...)
 
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