Urgent Help Needed!

[Chase]

Hi to all!

 

An urgent question to ask but a bit taxing on the math, so please bear with me:

 

A) If I'm currently on 185/60/14 tyres, the best upgrade if I want to use 16" rims are 215/40/16 tyres. Only 0.14% difference andwon't affect my speedo reading that much.

 

But what if I want to use only 205mm width tyres?

 

B) Can I use 205/50/16 tyres, which give me a 5.85% difference, meaning if I'm running at 119.25km/h, my speedo is actually only reading 112.65km/h. About 6km/h difference. Will this be very detrimental?

 

C) I know the best 205 width is 205/40/16, cos there's only -1.25% difference in circumference> ie.e If I'm running at 112.29km/h, the speedo shows 112.65km/h, only 1km/h difference.

 

My problem is, I'm taking over second hand 16" rims from someone. He's on (B) tyres which will give me a bigger difference in speedo readings. He won't sell the rims w/o tyres at a lower cost. So I have to either take over the tyres and sell them off (very new) or use them for myself.

 

What do you guys think? Should I save some money at the expense of speedo readings for a while, or lugi a bit and buy the correct tyre size?

[Pauly75ts]

Hi! there, Chase,

 

If it's cost that you're worried about, use the tyres until the next change. Does the wheels fit your car? BTW, 205/45/16 seems to be better.

 

Rgds

 

Paul Yong

[Chase]

HI Paul!

 

Thanks for the swift reply!

 

205/45/16 is my (D) tyres! hahaha!

 

It still gives me a 2.3% difference to my rolling diameter. So when I'm travelling at 112.65km/h, the speedo shows 115.23km/h. Also slightly off.

 

Much as I want to save cost, other considerations like safety and possible damage to car parts (eg. bushings? suspension?) also come into play. If I use the 205/50/16 that comes with the 2nd hand rims, the tyres thicker and my overall wheel diameter will increase about 1". Is that ok?

[Yongwd]

JM,

 

Take the difference from 175/70R13 for City since stock calibrated this model, not 185/60R14

[Presea]

I agree. The tyre size seems to be a little odd.

 

Chase, your speedo may not be reflecting the correct speed at the moment.

I think 185/65R14 would be the original Plus 1 option from the 13" rim.

195/55R15, 205/45R16 and 205/40R17 are the logical plus sizes.

[Chase]

Bro i don't get what you mean.

 

City VTEC uses 185/60/14 leh. Confirmed using electronic devices like RSM, HKS Turbo timer etc. You mean we gotta follow the City 13" spec? Why?

[Chase]

My car came with stock 185/60/14 tyres leh. You mean they are not calibrated properly even from factory? Figures are quite consistent from City drivers who installed electronic devices like RSM, HKS Turbo timer etc...

[Yongwd]

the stock meter is calibrated based on 13" rim, even if came with 14" alloy rims, it was simply a direct upsize from factory.

 

refer to the manual for minimum tyre specs. if the tranny is the same, always follow the minimum tyre size design for the vehicle and upsize accordingly, u will never go wrong

 

Take for example G9 1.5L should not follow 1.6L tyre size, the 2 platform shares a total of 4 different tranny. For City is simple.

 

if u dun understand wat am I toking about, gimme a buzz

[Presea]

as you said plus minus 1 kmh, you wouldn't know would you?

 

You can run against the kilometre markings along a straight stretch, and use a stop watch. Holding the speedo exactly at 120, it should take exactly 30s from 1km marking to the next.

 

Don't use Singapore km marks....not accurate.

Along NS highway....there are many straight stretches (flat ground).

 

Try to orientate your body with the left A frame of your car, and when all 3 elements are aligned, you, the A frame and the kilometre marking, that should be the right point to start and stop timing.

 

If you are accurate in timing...

 

120kmh = 2km per 60s = 33.333m per 1s

0.1s = a diff of 0.4kmh

 

for the fun of it, you could try timing it at 180kmh

180kmh = 3km per 60s = 50m per 1s

0.1s = 0.9kmh

 

cheers

Edited October 18, 2002 by Presea

[Cool]

Chase..

 

There is a calculation for the right tyre size. I think there is website on the calculation or maybe shaggy can advise you.

 

Give shaggy a call, if you do not have his number...call me.

[Chase]

Orh.... I think I get what you mean liao.

 

Cos the smallest rims for the City is 13" so even if City VTEC is on 14", it is just a one-up from the 13" specs. Right? So if I upgrade to 16", I should use 175/70/13 as the base number to start with. Tio bo?

 

Thanks bro, I think I know what to do now! =)

 

BTW, what do you think if I run on the oversized tyres and let the speedo read off for a few months, so that I can save some money for better new tyres?

[Chase]

wah a bit cheem... must digest...hehe

[Chase]

Bro!

 

I know the website for tyre size calculation.

 

My question is, I'm thinking of using the second hand tyres that come with the 2nd hand rims that are a bit oversized for my specs. The result will be that my speedo will be off by +6kmh... I just wanna know if there will be drastic problems cos of this, cos I don't wanna damage my suspension bushings etc...

[Cool]

Wah.. I really dunno la.

 

BTW.. where is the website ? I was looking for it

 

cheers.

[Chase]

Bro this is the brilliant website:

 

http://www.fernblatt.com/longhurst/tyre_bible.html#sizes

 

Key in your tyre sizes and hey presto! It's out!

[Geewhiz]

Hi, Cool,

 

attached is a " tire calculator", I hope you find it useful.

 

Don't remember where I got it from or from whom...................

 

could be from the Forum, who knows.................

tyrecal.xls

[Cool]

Thanks guys.. getting new rims this weekend for my MPV.

[Chase]

JM,

 

Take the difference from 175/70R13 for City since stock calibrated this model, not 185/60R14

Hey bro, just to confirm, I called up Kah motor and they said they calibrated the City VTEC to 14" rims instead of 13" rims leh. So the speedo won't run....are they having me on? How to verify? Write to Honda Thailand!