Which size tyres for IVA

[Peter-C]

I'm a bit confused over what size tyre to fit. I'm using the sierra gearbox and speedo and I want to make sure that the speedo readings are within IVA spec.
The sierra original tyres were 185/65 R14 and I am looking at Toyo T1R's. The perfect match are 195/55 R15's at Approx £60 each whereas 195/50 15's are £36 each.
Will the cheaper ones be ok. I assume that the speedo will read less than actual.

Cheers

Peter

[davedew]

Gus's car went through IVA with 195/50/15 tyres, so go for the cheaper ones.

[Peter-C]

Cheers,

Thats was what I wanted to hear.

Peter

[Bonzo]

Hi Peter

As far as I know, 50 is the correct aspect ratio for a 15" Sierra wheel rim

This will ensure that the circumference of the wheel is correct for the Sierra's speedometer

I have a set of Toyo TR1's for my own build & they are 195/50/15

[Peter-C]

Cheers Ronnie,

I used this website for comparison.

http://www.etyres.co.uk/tyre-size-calculator.htm

I was sure that a lot of people were using the 50 profile ok.

Peter

[Bonzo]

Hi Peter

I use this site for reference.

Alloywheels.com

That said, I notice in the Haynes manual that both 195/65/14 & 195/60/14 were fitted to various Sierra models as standard.

195/60/14 had a V rating

Hope I am not confusing the issue too much
Perhaps the tyres speed rating has a bearing on the aspect ratio of the tyre ?

[AshG]

forget t1r's fit r1r's they stick like poop to a blanket compared to the t1r's which i now consider to be rubbish after fitting r1r's. i would guestimate that i have about 40% more grip now with the r1r's

[AshG]

my car will be 2 years old in jan and i have already been through three sets of tyres. track days are fun

[Peter-C]

Cheers lads,

Are R1R's track use only ?

Peter

[HandyAndy]

I,ve just done a tyre size comparison between

185 / 65 / 14 = total tyre diameter =596mm

195 / 50 / 15 = total tyre diameter =576mm

so does this mean the speedo will under read ?

cheers
andy