Maximum Tyre size

Hi Crusier,

I bought a 2003 GX 2nd hand and the original tyres are soon to be replaced. I am going to replace the AT20 tyres with an off road tyre.

The only problem is the GX rims are only 6 inches. King rims make a 17inch by 8 inch rim which is around $130 to $150 depending on who to ring. To keep the GX legal, which I'm keen to do, I have only found the Cooper tyres to have the 245/70-17 size tyre which has a dia of 780mm.

From my calc 780mm is as big as I can go without going over the Vic requirement of max of 15mm increase on the largest tyre available for the 4wd. The 265/70-17 Cooper tyres are 803 mm dia. I don't think the 245 width will need a flare fitted.

Cheers Anthony

As mentioned, the GX has 6" wide rims. A 265mm wide tyre (the 265, from a 265/65R17), is too wide to be mounted on a 6" wide rim. You would need to upgrade your rims to a 7" wide version (like the GXL rims) for those tyres. You would also need flares (the rubber flexi-flares for the wheel arch work well to avoid needing the whole fibreglass/plastice flare kit) as the wider wheels will now protrude on a GX in order to be legal.

My memory might be wrong (as it often is), but I remember reading something about the lastest GX prodos (release from December 2006) having 7" wide rims on them, rather than 6". Worth investigating anyway.

Hope the info helps.

With the GX standard tyres 225/70-17, I believe that the speedo is not reading the correct speed. With the 225's when the speedo reads 100ks, I think the actual speed being travelled is around 97k's.

If I put on the standard GXL tyres, the 265/65-17's then I think the speedo would be correct. The 225's (using the tyre calc link provided above) are 747mm dia and the std GXL tyres are 776mm dia. The 245/70-17 are 774mm by the calculator but the Cooper tyre guide says the ST abd STT's are 780mm dia.

I want to put a decent off road tyre but they won't fit on the GX rims, so instead of getting expensive GXL rims, an option is to get the King rims (8 by 17 inch). I don't think the GX would need guard flares if I fit the 245/70-17 tyres on the 8 by 17 rims but I would need flares if I went with the 265/70-17.

The 245/70-17 and almost the same diameter as the standard GXL tyres. So the speedo should read the actual speed being travelled and fingers crossed I wont need to fit flares. If I'm wrong then Flexi Fares should be fine.