Alloy Wheels - R14 to R15 - implications?

Hello,

Could anyone please let me know what are the implications of going for a higher radius wheel from existing R14 to R15.  I intend to replace the existing 175/75 R14 with 185/65 or 190/65 ones. Not decided on the radius yet.

Would it affect the performance of the car in terms of mileage or handling?   I know the wider tyres would reduce the mileage by 1-2 km. But what would be the effect of increased radius?

Does the speedometer / odometer need any re-calibration?

How good are the "Plati" & "League" brands for alloy wheels? Are there any other good brands apart from these two?

Thanks

Chandan

Dear Chandan,

You can put the rim of any size as long as the outer radius of the tyre does not make a difference of more than 3 %. How to calculate the outer diameter, I will tell you. The OE tyre size you are planning to upsize is 175/75 R 14 That means, your tyre is having a width of 175 mm and sidewall hight of 131.25 mm (75% of 175). So the outer diameter of the tyre will be 356 mm (14 inch) + 262.5 (adding up two sides). ie, 619 mm. You can upsize the tyre keeping the outer diameter at  619 ± 19 mm. (you can increase the rim width by reducing the tyre profile.)

Another thing to keep in mind, when you increase the width of the tyre, for an increase of 20 mm, (ie, from 175 to 195) you are adviced to increase the rim width by 0.5 inch. While increasing the rim width, keep in mind that the offset of the rim should move to the negative side so that the distance from the spokes to the car body side remains the same and the extra width given to the tyre will protrude outwards only. Again the rough thump rule is when you are increaseing the width of the tyre by 20 mm, move the offset to the negative side by 20 (you should match the availability of tyres, rims while performing this.)

If you are following this, your car's performance will not be affected where as you get better road holding as well as aesthetics for your car. The fuel efficiency may drop to 0.5 to 1 km per liter, not more than that. I like League for their designs. Other good brands avlbl in market are Neo, Aura(Hindalco), Wheelz (apollo tyres)etc. Your Speedo/odo doesn't need any sort of recalibration since you are not changing the overall outer dia.

 In case of any doubt you can contact me at +97633 12645 (Pune). Wish you happy motoring days

Best regards,

Bijo Thomas

Dear Chandan ,

As you are replacing your steel rims with Alloys , you can go with any tyre , i would prefer you the 205/70 R 15 yokohoma or Bridgestone tyres along with PLATI Alloys , you could also try the AURA Alloys

another option would be 195/60 R 14

I feel 15 " 205/70 would be good

Cheers,

Sri

Depends on the clearance you have on the car model in question - anyway, a bigger question really is - why would you like to do it in the first place.

Most Manufacturers (all infact) do extensive R and D in terms of deciding the type of tyres for a car - So, I would go by the specs really. Car Tyres would be least possible point for any manufacturer to cut costs on !!

If you still want to change, then, be prepared for the following:

1. Mileage drops by about 5-10%

2. More frequent wheel Alignments would be needed - owing to the additional weight distribution.

3.  Speedometer and Odometers need to be recalibrated

4. Tyre wear might be more if wheel alignments are not done properly.

First of all, my apologies for my overdealyed response

Thank you guys for all your valuable inputs.

In the meanwhile, I managed to buy the car, for which i started this discussion   It's a new verna(crdi sx), which comes with 175/70 R-14(my mistake on quoting it initally as 175/75). I could not afford to go for an wheel upgarde as i went brankrupt by then   However, i would still like to go for an ugrade someday(not sure when) - Yes sir, inspite of all the right things that Mr. Kvsk Prasad has pointed to, i would be doing it for the sake of looks.

So here is new question for you guys.

1. Does anyone happen to know the offset of the stock wheels of verna?

2. And I have a question for Mr. Bijo Thomas : regarding offset - If i go for a tyre width of 195 & increase the rim width by 0.5 or 1 inch{my model has a rim width of 5j & for 195mm tyre width, Michelin(which i intend to go for), recommends a min of 5.5j & preferably 6j} - does it mean i have to make sure that the new alloy wheel has an offset that is 25.4mm(for an increase of 1j) less than the stock wheel offset? I am assuming 1j = 1inch(=25.4 mm).

Thank You!

hi candan , i think the latest Vernas comes with 185 / 65 14 tyres!

incase yours is 175 " then you could change it for 195 / 70 R 15 tyres

Alloys is not really necary !

Cheers,

Sri

Dear Chandan,

You are absolutely right. rim 5 J means the width is 5 inch. The offset you have to reduce 1 inch. You can calculate the offset of your present rim as follows:

Keep the rim horizontally on a flat surface, keeping the bolt side down. Measure the rim width (a). again, measure the backspacing of the rim (back spacing means, the distance from the spokes surface (inside the rim) to the end of the rim.(inside end). Now Offset = Back Space - (Rimwidth/2)

Just imagine, if the spokes are exactly at the centre, we know the offset is zero. We can prove this mathematically by the above equation, as follows

Offset = 3 - 6/2 = 0 (where 6" is the rim width, Back space = 3" since it is exactly at the center)

Hope your doubt is almost clarified

Bijo Thomas

actually since he is changing to alloy wheels it always better to put 5.5 " rim size, the rim that presently which comes in the swift is 5 " so upgrading would be better and help in putting other wheel size of 15" too

Cheers,

Sri