Fiat Panda 100hp - Increase Tyre Size Reduce wheel size

Honest John Back Room » Technical matters
View Threaded
Wed 1 Feb 2012 16:27
Fiat Panda 100hp - Increase Tyre Size Reduce wheel size - JP Furriskey

My Panda 100hp just failed first MOT with worn ball joints at 25,000 miles. I believe cause most likely overwide tyres on standard suspension components. Therefore considering fitting normal wheels with deeper profile tyres. Anyone know what size wheels & tyres I need to maintain same overall size as at present? Better ride also hopeful outcome.

Reply | Report as offensive | Link
Wed 1 Feb 2012 17:06
Fiat Panda 100hp - Increase Tyre Size Reduce wheel size - Peter.N.

A tyre shop should be able to tell you but if you go down one size in width and up one in profile that's usually about right, it should certainly improve the ride - I hate low profile tyres they have ruined the ride of many a good car.

Reply | Report as offensive | Link
Wed 1 Feb 2012 17:28
Fiat Panda 100hp - Increase Tyre Size Reduce wheel size - unthrottled

You can do it yourself on the back of an envelope.

For instance my wheels are 175/70R13

Multiply the width of the tyre (175mm)by its aspect ratio (0.70) to give the approximate sidewall thickness.

So for my car 175*0.70=122.5mm

Multiply by 2 (the side walls are on both side of the wheel!)

=245mm

divide by 25.4 to turn it into proper units

=9.65"

Add this to rim diameter (13")

Total diameter=22.65"

Don't worry about getting the new tyre to the exact same diameter-your speedo will over read by up to 8% anyway. +/-2% from the OEM diameter is perfectly adequate.

If you go down more than 1 wheel size, be careful that the rim provides sufficient room for the brake calliper.

Reply | Report as offensive | Link
Wed 1 Feb 2012 20:22
Fiat Panda 100hp - Increase Tyre Size Reduce wheel size - dieselweasel

Not sure if its the tyres. Wifes 1.3 diesel panda with 17k failed its first with worn bushes in suspension lower arms. Her car has skinny high profile Michelin energy tyres.

I reckon its speed humps/rubish roads, and weedy suspension components.

Fancy a wheel swap ? I love the panda but its spoilt by the lack of grip on the skinny tyres !

Reply | Report as offensive | Link
Thu 2 Feb 2012 14:03
Fiat Panda 100hp - Increase Tyre Size Reduce wheel size - JP Furriskey

Thank you- I need to keep these wheels for when I sell it. Yes, same thing, lower ball joint- but some seem to last over 70,000 miles others go young. Otherwise nice car.

Reply | Report as offensive | Link
Thu 2 Feb 2012 14:01
Fiat Panda 100hp - Increase Tyre Size Reduce wheel size - JP Furriskey

Thank you- & I agree 100% re low profile tyres

Reply | Report as offensive | Link
Thu 2 Feb 2012 14:01
Fiat Panda 100hp - Increase Tyre Size Reduce wheel size - JP Furriskey

Thank you! Maths O level was over 40 years ago but I will give it a whirl

Reply | Report as offensive | Link
Thu 2 Feb 2012 14:58
Fiat Panda 100hp - Increase Tyre Size Reduce wheel size - Paul G1pdc

www.miata.net/garage/tirecalc.html .

USE THIS LINK.... WILL SAVE YOUR MATHS SKILLS.

PAUL

Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide

Cold-snap snow-how: Advice on coping with the freezing weather, including videos, facts and winter driving advice.

Honest John's Guide To Winter Tyres